gettingstartedcpp - full.pdf

7/23/2019 GettingStartedCpp - Full.pdf

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Outline

Preparation

Getting Start

OOP

Memory management

Rest of C/C++ features

Appendix2


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Outline

Preparation

Getting Start

OOP

Memory management


Appendix

Hello world

C/C++ files

Entry point

C/C++ libraries

Source compile process

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Outline

Preparation

Getting Start

OOP

Memory management


Appendix

Variables and constant

Primary data type

Array Pointer String

Data structure: enum union - struct

Function

Namespace

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Outline

Preparation

Getting Start

OOP

Memory management


Appendix

Class & Object

Inheritance

Polymorphism

Operator overloading

Class static member5


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Outline

Preparation

Getting Start

OOP

Memory management


Appendix

Recall pointer

Memory leak

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Outline

Preparation

Getting Start

OOP

Memory management


Appendix

Forward declaration

Standard IO Console IO & FILE

Template

Type casting

Exception handling

Endian

STL introduction

GNU GCC/G++ 7


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Outline

Preparation

Getting Start

OOP

Memory management


Hello world!

C/C++ files

Entry point

C/C++ libraries


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Outline

Preparation

Getting Start

Basic Data Structure

OOP

Memory management


Hello world!

C/C++ files

Entry point

C/C++ libraries


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Hello world using VS

10


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Hello world

# include

void main()

{

printf("Hello world");

}

main.cpp

Use standard IO lib

Entry point

Print to console screen

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Outline

Preparation

Getting Start

OOP

Memory management


Hello world!

C/C++ files

Entry point

C/C++ libraries


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C/C++ source files

Header file (.h) aka include file

Hold declarations for other filesuse (prototype)

Not required

#include"stdio.h"

void Todo1();

void Todo2();

# include"header.h"

void Todo1()

{

Todo2();

}

void Todo2(){}

void main()

{

Todo1();

}

Source file (.c / .cpp)Content implementation

Required

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Outline

Preparation

Getting Start

OOP

Memory management


Hello world!

C/C++ files

Entry point

C/C++ libraries


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Entry point

Required unique entry point

The most common is: mainvoid main()

{

// your code here

}

Form1.cpp

int main(int n, char ** args)

{

// your code here}

Form2.cpp

1>LINK : fatal error LNK1561: entry point

must be defined

Error when no entry point is defined

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Outline

Preparation

Getting Start

OOP

Memory management


Hello world!

C/C++ files

Entry point

C/C++ libraries


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C/C++ standard library

C/C++ support a set of internalbasic library, such as

Basic IO

Math

Memory handle

For using, include the header

file#include

#include ""

#include"stdio.h"

void main()

{

printf("hello");

}

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C header C++ header

Content assert macro, for debugging

For character classification/convert functions

For testing error number Floating point macros

Define range of value of common type

Mathematical functions

Provide non-local jumps for flow control

Controlling various exceptional conditions

Standard lib

Standard IO

Manipulating several kinds of string

Converting between time & date formats

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C/C++ user-defined lib

Not C/C++ standard lib

Come from:

Third-party User own

In common, include 2 parts

.h files & .lib files: for developer

.dll file (dynamic library): for end-user

error LNK2019: unresolved external symbol

Error caused when forget to add .lib file

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C/C++ user-defined lib (cont.)

For using

Include .h files

Inform .lib files to compiler

Copy all .dll file to (if any) :

o same folder with execute file, or

o to system32 (windows) not recommend

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Declare path to .lib

Import user-defined library

Visual studio

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Import user-defined library

Visual studio

Declare .lib file

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Outline

Preparation

Getting Start

OOP

Memory management


C/C++ files

Entry point

C/C++ libraries

Hello world!


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Process

Source

.h/.c/.cpppreprocess

Preprocessedsource

Compile

.o / .obj

(object file)LinkerExecutable/

lib

Tools:

Visual Studio: cl.exe (Press F7 / F5)

GNU GCC: gcc/ g++

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Outline

Preparation

Getting Start

OOP

Memory management



Primary data type

Array Pointer - String


Function

Namespace

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Outline

Preparation

Getting Start

OOP

Memory management



Primary data type



Function

Namespace

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Variable classification

Scope:

Local variable

Global variable

Static variable

Storage class specifier

auto

static

register

extern

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Global & localintmGlobalVar;

void Foo()

{

intlocalVar;printf("Foo : %d %d\n",

localVar, mGlobalVar);

}

int main()

{

intlocalVar = 1;

printf("Main: %d %d\n",localVar, mGlobalVar);

mGlobalVar = 1;Foo();

return 1;

}

Global variable

Available in all of program

Set default value to zero

Local variable

NO default value

Available inside block

Main: 1 0

Foo : 2280752 1

Command prompt

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Auto variable

As default, a variable is a auto variable

intmyVar auto int myVar

Go out of scope once the program exits from the

current block

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Static variable

Allocated when the programstarts and is deallocated whenthe program ends.

Default value is zero (0)

#include

staticints_iGlobalStatic;

void Foo()

{

staticints_iLocalStatic;printf("Foo: called %d\n",

s_iLocalStatic++);}

int main()

{

int localVar = 1;printf("Main: %d\n",

s_iGlobalStatic);Foo();

Foo();

Foo();

return 1;

}

Main: 0

Foo: called 0

Foo: called 1

Foo: called 2

Command prompt

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Register variable

Stored in a machine register if

possible

Usually used in for iterator

for improve performance

int main()

{

int sum = 0;

for (registerint i = 0;

i < 100;i++)

{

sum += i;

}

printf("Sum = %d\n", sum);

return 1;

}

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Extern variable

Specify that the variable isdeclared in a different file.

Compiler will not allocate

memory for the variable

Avoid duplicate declaration

Share (global) variable formultiple .cpp files

#include

externint m_iExternVar;

int main()

{

printf("Value = %d\n",m_iExternVar);

return 1;

}

main.cpp

int m_iExternVar = 100;

Extern.cpp

Value = 100

Command prompt

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Constant

Variable's value is constant

To prevent the programmer from modifying

intconst k_Hello = 0;

int main()

{

k_Hello = 10;

}

error C3892: 'k_Hello' : you cannot assign to

a variable that is const

Error

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Outline

Preparation

Getting Start

OOP

Memory management



Primary data type



Function

Namespace

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Primitive data type

(32bits processor)Type Size Range

void n/a

char 1 byte unsigned char: -128 127

signed char: 0255

short 2 bytes unsigned short: 0 (216 -1)

signed short: -215 (215 1)

int 4 bytes

-231 (231 1)unsigned int: 0 (232 -1)

signed int: -231 (231 1)

long 4 bytes

-231 (231 1)unsigned long: 0 (232 -1)

signed long: -231 (231 1)

long long 8 bytes

-263 (263 1)unsigned long long: 0 (264 -1)

signed long long: -263 (263 1)

bool 1 byte True /false (non-zero / zero)

float 4 bytes

double 8 bytes 35


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New type definition

Use typedef

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typedefint Mytype;

typedefint MyArr[5];

Mytype var1;MyArr arr;


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sizeof operator

0Return size (in byte) of a type, data structure, variable

int sizeInt = sizeof(int);

int sizeLong = sizeof(long);

char a;

int sizeA = sizeof(a);

Return 4

Return 4

Return 1

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Outline

Preparation

Getting Start

OOP

Memory management



Primary data type



Function

Namespace

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Array

Used to store consecutive values of the same data types

int b[4] = {1, 2, 3, 4};

n-dimensions array

int b[][][] si MUST BE constant

Index of array is counted from 0 to (si-1)

C/C++ do not handle out-of-range exception

int b[4] = {1, 2, 3, 4};

for (int i = 0; i < 4; i++){

printf("%d\n", b[i]);

}

printf("%d\n", b[10]);

b[10] = ?

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Array Assignment

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int a[4] = {1, 2, 3, 4};

int a[] = {1, 2, 3, 4};

int a[4];

a[0] = 1;

a[1] = 2;

a[2] = 3;a[3] = 4;

int a[4] = {1};

a[0], a[1],

a[2], a[3] = ?

int a[4];

memset(a, 0, 4*sizeof(int));


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Array Assignment

2D Array

41

int a[3][2];

a[0][0] = 1;

a[0][1] = 2;

a[1][0] = 3;

a[1][1] = 4;

a[2][0] = 5;

a[2][1] = 6;

int a[3][2] = {1, 2, 3, 4, 5, 6};

int a[3][2];

memset(a, 0, 6*sizeof(int));

int a[][2] = {1, 2, 3, 4, 5, 6};

Same as

1D. Why?

int a[3][2] = {

{1, 2},

{3, 4},

{5, 6}

};


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Pointer

Computer's memory is made up of bytes.

Each byte has a number, an address, associated with it.

0x01 0x02 0x03 0x01 0x05 0x06 0x07 0x08

When storing a variable, such as inti = 1

0x00 0x00 0x00 0x01

0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08

i

o i = 1

o &i = 0x01 & operator: get address of a variable

42
http://augustcouncil.com/~tgibson/tutorial/addressDef.htmlhttp://augustcouncil.com/~tgibson/tutorial/addressDef.html


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Pointer (cont.)

For storing address of a variable, use a special type:

pointer

int *pi; char *pc; float *pf;

Pointer of a

integer variablePointer of a

char variable

Pointer of a

float variable

int *pi = &i;

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int* pi;

pi = &i;

0x10 0x00 0x00 0x00

0xF1 0xF2 0xF3 0xF4 0xF5 0xF6 0xF7 0xF8

i

&i


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Pointer (cont.)

Pointer is also a variableits stored in memory

int i = 10;int *p

i = 100x2f00002c

0x2f00aabb p

p =

&p =

*p =

*p : get value at address pointed by p

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0x2f00002c

0x2f00aabb

10

= &i;

= 0x2f00002c


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Pointer (cont.)

Type of pointer notify that how to get the value

pointed by pointer

int i = 0x3f20cc01;char *p1 = (char *)&i;

short *p2 = (short *)&i;

int *p3 = &i;

p1 is pointed to char-block. *p1 =

p2 is pointed to short-block. *p2 =

p3 is pointed to int-block. *p3 =

P1 P2

0x01 0xcc 0x20 0x3f

0xF1 0xF2 0xF3 0xF4 0xF5 0xF6 0xF7 0xF8

iLittle Endian

P3

45

0x01

0xCC01

0x3f20cc01


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Pointer (cont.)

sizeof operatorSize of pointer is not belong to type of pointer

Size of pointer depend on processor (16 bits, 32 bits, 64bits)

For windows 32 bits: size of pointer is 4 bytes

int main()

{

char c = 0;

char *p = &c;

printf("size = %d", sizeof(p));

}

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Pointer

pointer operatorNote: each step is a distance k bytes

belongs to type of pointer:

byte: 1 byte

Short: 2 byte .

Operat

or

desc Example

+ move forward n steps p += 10;

- move backward n step p -= 1;

++ move forward 1 step p++;

-- move backward 1 step p--;

0x01 0xcc 0x20 0x3f 0x00 0x10 0xaa

0x01 0x02 0x03 0x04 0x05 0x06 0x07

p1 p1+1 p1+5

0x01 0xcc 0x20 0x3f 0x00 0x10 0xaa

0x01 0x02 0x03 0x04 0x05 0x06 0x07

p2 p2+1 p2+3

char *p1; short *p2;

(p1+1) (p2 + 1)*(p1+1) *(p2+1)

&(p1+1) &(p2+1)

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Pointer

pointer operator - Practice

48

char a[6] = {10, 20, 30, 40, 50, 60};

char *p = a;

a

0x001cff08

p0x001cff04

a = ?

&a = ?

*a = ?

p = ?&p = ?

*p = ?

p + 1 = ?

(*p) + 1 = ?

*(p + 1) = ?

&p + 1;

&a + 1a++; a = ?

p++; p = ?


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Pointer to pointer

Recall that, a pointer variable is a variable.

To store address of a pointer variable, we use pointer-to-pointer variable.

49

int iVar = 10;

int *p1 = &iVar;

int **p2 = &p1;

iVar = 10

p1 = 0x100

p2 = 0x200

0x200

0x100

0x300

*p1 == ?

*p2 == ?

*(*p2) == ?


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p

nx4 bytes

Pointer

Dynamic allocation Static allocation:

int a = 10;

int array[1000];

Variable will be allocated in stack limited size

Number of elements of array is const

Can not clean up when they become useless

Dynamic allocation User pointer

Allocation a block of memory in heap high capacity

Clean up easily

Alloc n-int elements in heap

int *p = newint[n];

p

Free memory block pointed by p

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delete p;

How about

p after

deleting?


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Pointer

Dynamic allocation (cont.)There two way for dynamic allocation

51

Using stdlib.h Using malloc/free

Old C style

Using new/delete Using new[] / delete[]

C++ style

int main()

{

char *i = (char*) malloc (100);

// some code here

free(i);

}

int main()

{

char *i = new char[100];

// some code here

delete []i;

}


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Pointer

Dynamic allocation (cont.)Use delete for new,

Use delete[] for new[]

52

struct A

{

public:staticint count;

int val;

A()

{

printf("Created %d\n",

val = count++);}

~A(){

printf("Deleted %d\n",

val);}

};

int A::count = 0;

int main()

{

A *cA = new A[10];delete cA;

return 1;

}

Delete cA[0] only

int main(){

A *cA = new A[10];

delete []cA;

return 1;

}

Delete all cA


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Pointer-to-pointer dynamic

allocation

In common, used for allocation an 2D-array

53

int **p;

p = new int*[2];

*(p+0) = new int;

*(p+1) = new int;

p0x900

0x500

= 0x500

0x200

0x200

0x300

0x300

int **p = newint*[3];

p[0] = newint[4];

p[1] = newint[4];

p[2] = new int[4];

*(*(p + i) +j ) p[i][j]


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Pointer vs. Array

In common, pointer could be used like array

int main()

{

int *p

p[0] = 1;

*(p + 1) = 12;

p[2] = 5}

P

0x2f330000

0x2f330004

0x2f330008

0x2f0A0000

stack

heap

*p = *(p+0) = p[0]

*(p + n) = p[n]

54

newint [3];

= 0x2f330000

112

5

=


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Pointer vs. Array

Array is a pointer

pointed to itself

A pointer can point to

an array addr.

int main()

{

char a[3] = {1, 2, 3, 4};

printf ("0x%x 0x%x %d\n", a, &a, *a);

int *p = newint[3];

p[0] = 1; p[1] = 2; p[2] = 3;

printf ("0x%x 0x%x %d\n", p, &p, *p);

int *p2 = (int*)a;

printf("value of p2 = 0x%x\n", *p2);

}

0x14fd64 0x14fd64 1

0x591398 0x14fd60 1

Value of p2 = 0x04030201

Command prompt

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Pointer vs. Array

char a[3] = {1, 2, 3};

char *p = newchar[3];

p[0] = 10; p[1] = 20; p[2] = 30;

printf ("a = 0x%x p = 0x%x\n", a, p);

printf ("a+1 = 0x%x p+1 = 0x%x\n", a+1, p+1);

printf ("&a = 0x%x &p = 0x%x\n", &a, &p);

printf ("&a+1= 0x%x &p+1 = 0x%x\n", &a+1, &p+1);

a = 0x26FE6C p = 0x0E1AF0

a+1 = 0x26FE6D p+1 = 0x0E1AF1

&a = 0x26FE6C &p = 0x26FE70

&a+1= 0x26FE6F &p+1 = 0x26FE74

Command prompt

10

2030

1 a

0x0E1AF0

p

0x0E1AF1

0x0E1AF2

0x0E1AF3

0x0E1AF4

0x26FE70

0x26FE71

0x26FE72

0x26FE73

0x26FE74

0x26FE6C

20x26FE6D

30x26FE6E

0x26FE6F

&p + 1

&a + 1

56

a + 1

p + 1


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Due to stack limited, can not create a too big array

Pointer vs. Array

int main()

{

char arr[1034996];

}

int main()

{

char *p = new char[1034996];

}

FAIL OK

0Can not delete an arrayint main()

{

char arr[100];

delete arr;

}

int main()

{

char *p = new char[1034996];

delete p;

}

FAIL OK

Memory block of array is freed automatically when out-of-scope

Dynamic memory MUST be clean manually by call delete57


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Pointer vs. Array2D array

int arr[2][3]

pointer-to-pointerint **p = newint*[2];

p[0] = newint[3];

p[1] = newint[3];

[0][0] [0][1] [0][2]

[1][0] [1][1] [1][2]

p[1]

p[0]p p[0][0] p[0][1] p[0][2]

p[1][0] p[1][1] p[1][2]

02D array & 2D pointer could use in the same way

arr[2][2] = 5 p[2][2] = 10

58

[0][0] [0][1] [0][2] [1][0] [1][1] [1][2]

Block 0 Block 1

*(*(p + i) +j ) p[i][j]


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C/C++ String

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String

No standard string in C/C++

Use char*, or char[] instead

String in C/C++ is array of byte, end with \0

char *st = "String";

S t r i n g \0st

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String allocation

Static allocation


char st2[] = "String";

Dynamic allocation

char *st3 = newchar[6];

st3[0] = 's';

st3[1] = 't';

st3[2] = 'i';st3[3] = 'n';

st3[4] = 'g';

st3[5] = '\0';

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String allocation (cont.)

62

char* GetString1(){


return st;

}

char* GetString2(){

char st[] = "String";

return st;

}

char* GetString3(){

char *st = newchar[6];

strcpy(st, "String");

return st;

}

int main(){

printf("Say: %s", GetString1());



}

What are

different?


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Memory utility functions

MUST #include

void * memcpy ( void * destination, const void * source, size_t num )

Copies the values ofnum bytes from the location pointed

by source directly to the memory block pointed by destination

int memcmp ( const void * ptr1, const void * ptr2, size_t num )

Compare the C string pointed by source into the array pointed

by destination, including the terminating null character

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Memory utility functions

size_t strlen ( const char * str ) Returns the length ofstr

The length of a C string is determined by the terminating null-character

This should not be confused with the size of the array that holds thestring

char * strcpy ( char * destination, const char * source )

Copies the C string pointed by source into the array pointedby destination, including the terminating null character

int strcmp ( const char * str1, const char * str2 ) Compares the C string str1 to the C string str2.

http://www.cplusplus.com/reference/clibrary/cstring/64
http://www.cplusplus.com/reference/clibrary/cstring/http://www.cplusplus.com/reference/clibrary/cstring/


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Constant pointer vs.

pointer to constantConstant pointer:

Address of memory stored is constant

Value at address which pointed to could be changed

65

Pointer to constant: Value at address which pointed to is constant Address of memory stored could be changed

char char_A = 'A';

constchar * myPtr = &char_A;

*myPtr = 'J'; // error - can't change value of *myPtr

char char_A = 'A';

char char_B = 'B';

char * const myPtr = &char_A;

myPtr = &char_B; // error - can't change address of myPtr


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Outline

Preparation

Getting Start

OOP

Memory management



Primary data type



Function

Namespace

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Enum

Use for set up collections of named integer constants

In traditional C way:

Alternate approach

#define SPRING 0

#define SUMMER 1

#define FALL 2

#define WINTER 3

enum {SPRING, SUMMER, FALL, WINTER};

0 1 2 367


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Enum (cont.)Declaration

Values of enum constants

enum MyEnum{SPRING, SUMMER, FALL, WINTER};

enumMyEmum x; // C style

MyEnum y; // C++ style

int main(){

y = MyEnum::SPRING;

y = FALL;

y = 1; // ILLEGAL}

enum MyEnum{SPRING = 0, SUMMER = 10, FALL = 11, WINTER = 100};

int main()

{

y = MyEnum::SPRING;

printf("%d", y);

} 68


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Union

Allow same portion of memory to be accessed as

different data typeunion MyUnion

{

int iValue;char cValue;

char aValue[4];

};

int main()

{

MyUnion mine = {0x01020304};

printf("iValue: 0x%x\n", mine.iValue);

printf("iValue: 0x%x\n", mine.cValue);

printf("iValue: 0x%x 0x%x 0x%x 0x%x\n",

mine.aValue[0],

mine.aValue[1],

mine.aValue[2],

mine.aValue[3]);

}

0x04 0x03 0x02 0x01

iValue 0x01020304

0x04

0x04 0x03 0x02 0x01

cValue

aValue

Memory block

sizeof(mine) = ?

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Struct

Define a structure type and/or a variable of a

structure type.

struct T_MyStruct

{int val1;

char val2;

char val3[5];

};

struct T_MyStruct myStruct;

val1

val2

val3

T_MyStruct

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Struct

Using struct:typedefstruct T_MyStruct

{

int val1;

char val2;

char val3[5];

}MyStruct;

MyStruct myStruct;

int main()

{

myStruct.val1 = 10;

myStruct.val2 = 100;

myStruct.val3[0] = 1000;

}

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Data Structure alignment

Is the way data is arranged and accessed in computer

memory.

Consist two issue:

Data alignment:

oPut data at memory offset equal to multiple word size

Structure padding:

o Insert some meaningless bytes between the of last datastructure and start of next

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Data Structure alignment

0Before compile, total memory

of T_MyStruct is 8 byte

struct T_MyStruct

{

char val1;

short val2;

int val3;char val4;

};

char: 1 byte aligned

short: 2 byte aligned

int : 4 byte aligned

val1 val2 val3 val4

0 1 3 7

pad

1val2 val3 val4

0 1 2 3 4 8 9 10 11

val1

4 bytes block 4 bytes block 4 bytes block

pad2

4 bytes alignment

sizeof(T_MyStruct) == 12 bytes73


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VS Struct member alignment

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GCC alignment

75

struct test_t

{

int a;

char b;

int c;}__attribute__((aligned(8)));

struct test_t

{

int a;

char b;int c;

}__attribute__((__packed__));

http://www.delorie.com/gnu/docs/gcc/gcc_62.html

8 byte alignment

smallest possible alignment
http://www.delorie.com/gnu/docs/gcc/gcc_62.htmlhttp://www.delorie.com/gnu/docs/gcc/gcc_62.html


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Struct - function

C++ only, not availablein C

Beside variable, struct

also has had functionStruct alignment is not

effected to struct-function

Function is not countedwhen calculate structsize

typedefstruct T_MyStruct

{

int val1;

char val2;

char val3[12];

void SayHello();

}MyStruct;

void MyStruct::SayHello()

{

printf("Hello world");

}

int main()

{

MyStruct myStruct;

myStruct.SayHello();

}

76

S


77/245

Struct

constructor / destructorC++ only, not available in C

Two special function of struct

Constructor: automatically callwhen a instant of struct is created

Destructor: automatically callwhen a instant of struct is destroy


{

int val1;T_MyStruct();

~T_MyStruct();

}MyStruct;

T_MyStruct::T_MyStruct()

{

printf("Created\n");

}

T_MyStruct::~T_MyStruct()

{

printf("Destroy\n");}

int main()

{

MyStruct myStruct;

}

constructor

destructor

Created

Destroy

Command prompt

77


78/245

Struct and static member

Static function & static

variable

Static variable is not

counted is structalignment and struct

size


{

int val1;

staticchar val2;

staticvoid SayHello() {}

}MyStruct;

int main()

{

MyStruct myStruct;

printf("%d", sizeof(myStruct));

MyStruct::SayHello();

}

78


79/245

Struct and Access privilege

C++ only, not available in CThree access privilege methods

public: visible for allprivate: visible inside struct onlyprotected: visible inside struct and

retrieved struct (OOP)

Default ispublico For example: valx is public

79

struct MyStruct

{int valx;

public:

int val1;

private:

int val2;

protected:int val3;

};

int main()

{

MyStruct mine;mine.val1 = 0;

mine.valx = 0;

mine.val2 = 0;

mine.val3 = 0;

}

Fatal Error, val2 is private

Fatal Error, val3 is protected


80/245

Outline

Preparation

Getting Start

OOP

Memory management



Primary data type



Function

Namespace

80


81/245

C/C++ function

function_name([ ], [])

voidfoo() {}

voidfoo(int a, int b, char c){}

intfoo()

{return 1;

}

No return function

Required return

81


82/245

Default parameters

#include

void foo(int a,

int b = 1 ,

int c = 2 );

void foo(int a, int b, int c)printf("%d %d %d\n",

a, b, c);

}

void main()

{

foo(0);

foo(0, 10);

foo(0, 10, 100);

}

Set default value

Use b, c as default value

No default value

Use b, c as default value

0 1 2

0 10 2

0 10 100

Command prompt

82


83/245

void foo(int a, int b = 1, int c )

{

printf("%d %d %d\n", a, b, c);

}

Default parameters (cont.)

ERROR

error C2548: 'foo' : missing default

parameter for parameter 3

When a parameter is set default value, the

rest of next parameters MUST BE set

default value too

RULES

83

V i bl b f


84/245

Variable number of

parameters#include#include

int sum(int num_param, ... ){

int sum = 0, val = 0;

va_listmarker;va_start(marker, num_param);for (registerint i = 0; i < num_param; i++)

{

val = va_arg(marker, int);sum += val;

}

va_end(marker);return sum;

}

void main()

{

printf("%d\n", sum(1, 10));

printf("%d\n", sum(3, 1, 2, 3));

}84


85/245

Parameter classification

Value parameter

Reference parameter

Constantparameter

Const Referenceparameter

Pointer parameter

85


86/245


Pass-by-value

A copy of parameter is madeValue parameter

Reference parameter

Constant parameter


Pointer parameter

void foo(int n)

{

n++;

}

void main()

{

int x = 2;

foo(x);

printf("%d\n", x);

}

x = 2

2x2x

2n

2x

3n2x

foo86


87/245


Pass-by-reference

Actually parameter itself is passed

Use reference operator &

Value parameter

Reference parameter

Constant parameter


Pointer parameter

void foo(int&n){

n++;

}

void main()

{

int x = 2;

foo(x);

printf("%d\n", x);

}

x = 3

2x 2x

n

x3

n3x

foo87


88/245


Pass-by-value

A copy of parameter is made andstrict as const.

Value parameter

Reference parameter

Constant parameter


Pointer parameter

void foo(int cont n)

{

n++;

}

void main()

{

int x = 2;

foo(x);

printf("%d\n", x);

}

Fail, can not

modified

const value

2x2x

2n

2x

3n

foo88


89/245


Pass-by-ref

Actually parameter itself is passed but

avoid modify

Void the overhead of creating a copy

Value parameter

Reference parameter

Constant parameter


Pointer parameter

void foo(int const &n)

{

//todo

}

89


90/245


In common, Pass-by-value

A copy of parameter is madeValue of parameter is an address of a

memory block

Value parameter

Reference parameter

Constant parameter


Pointer parameter

void foo(int *n)

{

//todo

}

Value of parameter will not bechange,

but memory block which pointed

by parameter could be modified.90


91/245

Pointer Parameter

#include

void foo(int *A, int *B)

{

int *tmp = A;

A = B;

B = tmp;

}

void main()

{

int A[] = {1, 2, 3};

int B[] = {10, 11};

printf("0x%x 0x%x\n", A, B);foo(A, B);

printf("0x%x 0x%x\n", A, B);

}

A

B

A

B

A

B

A

B

Copy value

(addr. of data)

foo

0x29faa8 0x29faa00x29faa8 0x29faa0

Command prompt

91


92/245

Pointer Parameter

#include

void foo(int *A)

{

A[2] = 10;

}

void main()

{

int A[] = {1, 2, 3};

printf(%d\n", A[2]);

foo(A);

printf(%d\n", A[2]);

}

A

A

foo

12

3A[2] = 10 10

A

A[2] = 3

A[2] = 10

Copy value

(addr. of data)

92


93/245

Pointer reference parameter

A special case of pointer parameter

Value of pointer parameter (address of block memory) could be changed

Pass-by-reference

CAN NOT work with array directly

#include

void foo(int*&A, int*&B){

int *tmp = A; A = B; B = tmp;

}

void main()

{

int arr1[] = {1, 2, 3};int arr2[] = {10, 11};

int *A = arr1;

int *B = arr2;


foo(A, B);


}

A

B

A

B

A

B

A

B

foo

0x31fc90 0x31fc880x31fc88 0x31fc90

Command prompt

93


94/245

Function overloading

C++ only

Allow multiple functions with the same name, so long

as they have different parameters.

void Todo(int a)

{}

void Todo(int a, int b){}

94


95/245

Function Prototype

In C/C++, functions MUST BE declare before using.

To solve this problems Keep all functions in correct order

Use prototype inside .cpp file

Use prototype inside header (.h) file -> recommend

#include"header.h"void Todo1()

{

Todo2();

}

void Todo2(){}

int main(){}

Main.cpp

void Todo1()

{

Todo2();

}void Todo2()

{}

int main()

{}

Error

error C3861:'Todo2': identifier

not found

Main.cppheader.h

void Todo1();

void Todo2();

95


96/245

Extern function

Sometimes, we need to use a function in another

module (.cpp file)

Header file is too complicated to use (caused error

when used)

#include

externvoid TodoExtern();

int main(){

TodoExtern();

return 1;

}

Main.cpp

#include

void TodoExtern()

{printf("TodoExtern\n");

}

Extern.cpp

96


97/245

Extern C

Name mangling:

Aka name decoration

The way of encoding additional information in a name offunction, struct, class

In C++:

For adapting overload, class/struct functions, name offunction will be encoding

int f (void) { return 1; }

int f (int) { return 0; }

int __f_v (void) { return 1; }

int __f_i (int) { return 0; }97


98/245

Extern C

For mixing C and C++ source (Object C also) use extern"C"

Extern C talk to compiler that use C style for its scope No name mangling

No overloading

Extern C is also extern function could be implement in another module

#include

void ExternC()

{printf("ExternC\n");

}

Ansi_c.cextern"C"

{

void ExternC();

void Todo()

{

printf("%d", i);

}

}

C_plusplus.cpp

98


99/245

Extern C in practice

#ifdef__cplusplusextern"C" {

#endif

// your code here

#ifdef__cplusplus}

#endif

__cplusplus: default C++ preprocessor definition

99


100/245

Pointer to function

A variable store address of a function

Advantage

Flexible

User for event handling mechanism

// C

void DoIt (float a, char b, charc){}void (*pt2Function)(float, char, char) = DoIt;

// using

pt2Function(0, 0, 0);

100


101/245

Inline function

Macro: preprocessor replaces all macro calls directly

with the macro code

101

#define NEXT(a) (a+1)

int main(){

printf("%d", NEXT(1));

}

int main(){

printf("%d", (a + 1));

}


102/245

Inline function (cont)

Like macro, but obeys C/C++ syntax

102

inlineint Next(int x)

{

return x + 1;

}

int main()

{

printf("%d", Next(1));

}

For OOP, Inline function is allowed to set access privilege

Improve performance (for short/simple inline functions)

NOTE: The compiler is not forced to inline anything at all

Why

performance isimproved?


103/245

Outline

Preparation

Getting Start

OOP

Memory management



Primary data type



Function

Namespace

103


104/245

Namespace

A abstract container uses for grouping source code.

In C++, a namespace is defined with a namespace

block

namespacemaths {voidsin() {}voidcos() {}voidadd() {}

}

namespacematrix {voidmult() {}voidadd() {}

}

104


105/245

Using namespace

For using methods, variables, of a namespace:

::

namespacemaths {

voidsin() {}voidcos() {}voidadd() {}

}

namespacematrix {voidmult() {}voidadd() {}

}

voidmain(){

maths::sin();

matrix::add();

}105


106/245

Using namespace

Use using namespace for shorten way.

namespacemaths {voidsin() {}voidcos() {}

voidadd() {}}namespacematrix {

voidmult() {}voidadd() {}

}

using namespace maths;

using namespace matrix;voidmain(){

sin();

mult();

}

106


107/245

Namespace ambiguous call

More than two definition ofaddfunctions

maths::add()

matrix::add()

ambiguous call fatal error.

In this case, MUST BE specify

namespace.

namespace maths

{

void add();

}

namespace matrix{

void add();

}

usingnamespace maths;

usingnamespace matrix;

void main()

{

add();

}

error C2668: 'matrix::add' : ambiguous call to overloaded function

.\main.cpp(8): could be 'void matrix::add(void)'

.\main.cpp(3): or 'void maths::add(void)'

107


108/245

Outline

Preparation

Getting Start

OOP

Memory management


Class & Object

Inheritance

Polymorphism




109/245

Outline

Preparation

Getting Start

OOP

Memory management


Class & Object

Inheritance

Polymorphism




110/245

ClassAs same as structDefault access is private

110

class MyClass

{

public:

MyClass();

~MyClass();

protected:

int GetVal() {return m_Var;}

void Todo();

private:

int m_Var;

void SayHello();

};

void MyClass::Todo()

{

//some code here

}

Class name

Access methods

Constructor

Destructor

Function (methods)

Inline methods

Class variable (property)

Function implementation


111/245

Class (cont)

In traditional, code of class is divided into 2 parts

Declaration: in .h file

Implementation: in .cpp file

111

#ifndef__CCLASS_H__#define__CCLASS_H__class CClass{

public:CClass();

~CClass();private:

void Toso() ;

};

#endif

Any_name.h#include "Any_name.h"voidCClass::Todo(){

}

CClass::~CClass(){

}

Any_name.cpp


112/245

How to use class

112

MyClass objA; //or MyClass objA()

objA.SayHello();

Create a object directly

Access class methods,

properties by using dot

Create a object through pointer. Two ways to use methods,

properties

o (*objA). C style

o objA-> C++ style

Supported polymorphism

MyClass *ObjB = new MyClass;//or MyClass *ObjB = new MyClass();

(*objA).SayHello();

objA->SayHello();

Recommend!

MyClass *ObjB = new MyClass;

objA->SayHello();


113/245

Access methods

Aka Encapsulation

Public: allow access inside & outside class

Protected: allow access inside class & in derived class

Private : allow access inside class only

113
http://en.wikipedia.org/wiki/Encapsulation_(object-oriented_programming)http://en.wikipedia.org/wiki/Encapsulation_(object-oriented_programming)


114/245

Constructor

Should be public

Called when an instance is created

A class could define a set of constructors (constructor

overloading)

114

class MyClass

{

public:

MyClass();

MyClass(MyClass* A);

MyClass(const MyClass& A);

MyClass(int val);

}

Default constructor

Copy constructor.


115/245

Copy constructor

Definition:

A constructor with the same name as the class

Used to make a deep copy of objects (be careful if class

content pointer properties)

115

If no user-defined constructor is defined, compiler definesone.

X (const X& copy_from_me)

X (X* copy_from_me)

X (X& copy_from_me)

X (const X&copy_from_me, int = 10, float = 1.0 )

Must be set default value

C ( )


116/245

Copy constructor (cont.)

Invoked when

When a object is created

from another object of

the same type When an object is

passed by value as

parameter to function

When a object is return

from a function

116

class ABC{

public:

ABC(){}

ABC(ABC *A){printf("here1\n");}

ABC(const ABC &A)

{

printf("here2\n");

}};

void Foo1(ABC A){}

ABC Foo2()

{

ABC a;

return a;

}int main()

{

ABC *A = new ABC();

ABC B(A);

Foo1(A);

Foo2();

}

C ( )


117/245

Copy constructor (cont)

A default copy constructor is created automatically,

but it is often not what you want.

117

Image(Image *img) {

width = img->width;

height = img->height;data = new int[width*height];

for (int i=0; idata[i];

}

Image(Image *img) {

width = img->width;

height = img->height;data = img->data;

}

Automatic generated copy constructor User-defined (expected) copy contructor

E li i


118/245

Explicit constructor

"nonconverting"

Explicit constructor syntax is required.118

class A {

public:

explicit A(int) {}};

void f(A) {}

void g()

{

A a1 = 37;

A a2 = A(47);

a1 = 67;

f(77);

}

Without explicit With explicit

D


119/245

Destructor

Automatically invoked whenan object is destroy:

Out of scope

Or manually free (usepointer)

Use for collect class memory

119

class MyClass{

char m_Var;

int m_pData;

public:

MyClass(char id) {

m_Var = id;

m_pData = new int[100];

};

~MyClass() {delete m_pData;

cout


120/245

this pointer

A special pointer point to class instance itself

Used inside class, for access class methods, properties

120

class MyClass

{

char m_Var;public:

MyClass(char id) {m_Var = id;};

~MyClass() {}

MyClass* Todo1(int val)

{

if (this->m_Var == val)

{

return this;}

return 0;

}

void Todo2()

{

this->Todo1('A');

}

};

M b i i i li i


121/245

Member initialization

121

class MyClass

{

private:

int m_iVar1;

float m_fVar2;

char * m_pVar3;public:

MyClass();

}

MyClass::MyClass():

m_iVar1(10),

m_fVar2(1.3f),m_pVar3(0)

{

}

Setup value of properties

O tli


122/245

Outline

Preparation

Getting Start

OOP

Memory management


Class & Object

Inheritance

Polymorphism



I h it


123/245

Inheritance

Code reuse:

Composition: create objects of existing class inside the

new class

Inheritance: create a new class as a type of an existing

class

123

Existing class

New class

class NewClass

{

public:

ExistingClass *m_member;

};

Base class

Derive classHierarchy model

class Derive: public Base

{

};

I h it t


124/245

Inheritance syntax

124


{

public:

Derive():Base() {}

void Todo();

};

void Derive::Todo()

{

this->protectedFunc();

this->publicFunc();

this->privateFunc();

Base::Todo();

}

class Base

{

public:

Base() {}

void publicFunc() {}

void Todo() {}

protected:

void protectedFunc() {}

private:

void privateFunc() {}

};

FAIL: cannot access private member

Access bases method (same name)

Constructor init

I h it


125/245

Inheritance access

Base access Inherit access Derive access

Public

Public

Public

Protected Protected

Private PrivatePublic

Protected

Protected

ProtectedPrivate

Private

Public

Private privateProtected

Private

125

Inheritance access


126/245

Example

126

class CAnimal

{

public:

void Drink();

protected:

void Run();

private:void Eat();

};

class CRabbit: private CAnimal

{

public:

CRabbit(){

Run();

Eat();

Drink();

}

};

void main()

{

CRabbit rab;

rab.Drink();

rab.Eat();rab.Run();

}Why?

Constructor Destructor


127/245

Inheritance

127

Animal

Mammal

Lion

Lion *theLion = new Lion()

Lion()

Animal()

Mammal()

delete theLion;

~Lion()

~Mammal()

~Animal()

M lti l i h it


128/245

Multiple inheritance

A class could be inherit from multiple base class

128

Human

StreetMusician

Musician Worker

class Human{};

class Musician

{

public:

Musician(int instrument, int year){}};

class Worker

{

public:

Base2(int level){}

};

class StreetMusician: public Human,protected Musician,

private Worker

{

public:

StreetMusician(): Human(),

Musician(1, 1),

Worker(10) {}

};

Inheritance


129/245

Ambiguous access

CBase1::Hello()

CBase2::Hello()

129

class CBase1

{

public:

void Hello();

};

class CBase2

{

public:

void Hello();

};

class CDerive: CBase1, CBase2

{

public:

CDerive(): CBase1(), CBase2()

{

Hello();}

};

Ambiguous access of'Hello

How to

solve?

Outline


130/245

Outline

Preparation

Getting Start

OOP

Memory management


Class & Object

Inheritance

Polymorphism



Polymorphism


131/245

Polymorphism

Implemented in C++ with virtual functions

Virtual function

Pure virtual function

Pure virtual class (abstract class / base class)

Use for improved code organization

Extensible

131

Function call binding


132/245

Function call binding

Binding:

Connecting a function call to a function body

Early binding:

Binding is performed before the program is run by compiler,linker

Late binding:

Binding occurs at runtime, based on the type of the object

Aka Dynamic binding or Runtime binding

For C++, to cause late binding, use keyword virtual

132

Overriding vs Overloading


133/245

Overriding vs. Overloading

Overriding: override a

bases virtual or non-

virtual methods

Overloading: several

methods with the same

name which differ from

parameters

133

class Animal{

public:

virtualvoid Eat(){}

void Run(){}

};

class Cat: public Animal{

public:

//overiding

void Eat(){}

void Run(){}

//overloading

void Jump();

void Jump(int distance);

};

Virtual Overriding vs.

non-virtual Overriding

class Animal

{

public:

virtualvoid Eat()


134/245

Obj is a Animal pointer, but

really a Cat instant

Without virtual (early binding),Animal:Run was called instead

ofCat::Run

134

{

cout


135/245

destructor

When obj is freed, both

itself and base MUST BE

deleted

Its ok for obj1, but

problem for obj2

135

{

cout


136/245

( )

To solve this problem,

use virtual destructor

136

{

cout


137/245

Pure virtual classPure virtual function: Virtual function with no body

Pure virtual class:

Class content pure virtual function

CAN NOT create an instance of

pure virtual class directly

Derive class of pure virtual classMUST implements all pure virtual

functions

137

class Base

{

public:

virtualvoid Todo() = 0;

};


{

void Todo() {}

}

Outline


138/245

Outline

Preparation

Getting Start

OOP

Memory management


Class & Object

Inheritance

Polymorphism





139/245


Another way to make a function call

Define function of operator such as : +, -, *, /,

WARNING: Not recommend to use. Its easy to read,

but hard to debug !

139



140/245

example

140

class Integer

{

public:

int i;

Integer(int ii) : i(ii) {}

const Integer operator+(const Integer& rv)

{

return Integer(i - rv.i);}

Integer& operator+=(const Integer& rv)

{

i *= rv.i;

return *this;

}

};

int main()

{

Integer ii(1), jj(2), kk(3);

kk += ii + jj;

cout


141/245

Outline

Preparation

Getting Start

OOP

Memory management


Class & Object

Inheritance

Polymorphism



Static function


142/245

Static function

Allow user invokes

without creating an

instance

Declaration with statickeyword

No need to create

object, but must be

declared class name

142

class MyClass

{

public:

staticvoid Todo();

};

void MyClass::Todo()

{

//implemetation

}

int main()

{

MyClass::Todo();

}

Static variable


143/245

Static variable

Same as static function

Value of static variable

MUST BE set outside

class declaration.

143

class MyClass {

public:

staticint s_Var;

};

int MyClass::s_Var = 99;

int main()

{

printf("%d",

MyClass::s_Var);}

Lazy initialization


144/245

y

0The tactic of delaying the

creation of an object,

calculation of a value, or

some other expensiveprocess until the first

time it is need.

144

class ExpensiveRes

{public:

ExpensiveRes() {}

void todo1();

static ExpensiveRes* GetInstance();

private:

static ExpensiveRes* s_Instance;

};

ExpensiveRes* ExpensiveRes::s_Instance = 0;ExpensiveRes* ExpensiveRes::GetInstance()

{

if (!s_Instance)

{

s_Instance = new ExpensiveRes();

}

return s_Instance;}

int main()

{

ExpensiveRes::GetInstance()->todo1();

ExpensiveRes::GetInstance()->todo1();

}

Outline


145/245

Outline

Preparation

Getting Start

OOP

Memory management


Recall pointer

Memory leak

145

Question?


146/245

Question?

What does memory leak mean ?

How is memory structure ?

What does its consequences ?

Why does memory leak happen ?

How to detect and solve?

146


147/245

What does memory leak

mean ?First, How is memory structure ?

147


148/245

How is memory structure ?STACK vs HEAP

148

Run-time storage


149/245

Run time storage

Code segment:

where the compiled program sits inmemory

Global area:

store global variables

Stack segment:

where parameters and local variables areallocated

Heap segment:

where dynamically allocated variables areallocated

149

Text segment

(Code segment)

Stack segment

Heap Segment

Global area

Stack


150/245

Stack

Where parameters and local

variables are allocated

Limited sizeStack

overflowMemory use in stack is

temporary and auto release

Fast processing/low size

150

Parameters

Return Addresswhere to begin execution

when function exits

Dynamic linkpointer to caller's stack

frame

Static linkpointer to lexical parent

(for nested functions)

Return value

Local variables

Concept Stack frame

Text segment

(Code segment)

Stack frame

Heap Segment

Global area

Stack frame

Heap


151/245

Heap

Large pool of memory

Dynamic allocation

Stays allocated untilspecifically deallocated

leak!Must be accessed through a

pointer

Large arrays, structures, orclasses should be storedHeapwhy?

Large & dynamic

151

Parameters

Return Addresswhere to begin execution

when function exits

Dynamic linkpointer to caller's stack

frame

Static linkpointer to lexical parent

(for nested functions)

Return value

Local variables

Concept Stack frame

Text segment

(Code segment)

Stack frame

Heap Segment

Global area

Stack frame

Heap vs Stack


152/245

Heap vs Stack

int_array[10]; stored in stack

152

Stack

_array

int*_array = new int[n]

Pointer _array is stored in Stack Data of array is stored in Heap

_array0x00FF

Stack10

Heap

0x00FF

0x0005

Value of:

_array : address where int point into in heap (0x00FF) (*_array): value at it's address on heap (10) (&_array): address of the memory which used for stored pointer

_array in stack (0x0005)

FAQ


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FAQ

Why we use

Classname *Obj = new Classname();

instead of Classname Obj;

153


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Memory leak overview

154

What does memory leaking


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mean?Definition:

Particular type of unused memory, unable to release

Common:

Refer to any unwanted increase in memory usage* usually for heap memory

155

void Leak()

{

int *A = newint[1000];

// some code here// ...

// without delete A

//

return;

}

4000 bytes

Return without free A Leak



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Application gets slow fps

Application is crashed

Device has been freeze, restarted

156


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Why does memory leak

happen?First, Let's see some examples

157

Example 0


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Example 0 Forget to release resources

No GC mechanic supported

Button is

pressed

Save current floor

On target

floor ?

Wait until lift is idle

Go to required

floor

Release memory used to

save current floor

True

Finished Memory

Leaking

here

158

C/C++ Example 1


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void Fa()

{

}

void Fb()

{}

void Leak(){

int *a = newint[10];

Fa();

Fb();

return;

}

void main()

{

Leak();

}

C/C Example 1

Leak memory

caused by

lacking of releasedynamic memory

delete a[];

return;

Solution

Leak !

159

C/C++ Example 2


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C/C Example 2

voidleak()

{

int **list = newint*[10];

for (int i = 0; i < 10; i++){

list[i] = newint;

}

delete list;

return;

}

Allocation a series,delete only one unit

Leak !for (int i = 0; i < 10; i++){

delete list[i];

}

delete list;

Solution

160

C/C++ Example 3


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C/C Example 3

Leak memory when

using pointer-return-

type

delete []str;

Avoid to call directly GenString()

Solution

161

char* GenString()

{

char *a = newchar[10];

a[9] = '\0';

return a;

}

void Leak()

{

char *str = GenString();

printf("%s\n", str);

printf("%s\n", GenString());}

C/C++ Example 4


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#include

void Foo(){

int* a = newint[100];

a = newint[1000];

}

void Foo1()

{int* a = newint[100];

int* b = newint[1000];

a = b;

}

C/C Example 4Leak memory because ofmisunderstanding = operator in

C++

Stack

Heap

A

LEAK!

162

Leak!

C/C++ Example 5


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/ p

void main()

{

Classname *A = new A();

...

...

//free A

A = NULL;

}

163

Misunderstand free memory methodin C/C++

Stack

Heap

A

NULL

LEAK!

Keep in mind we are using C/C++

Use MACRO for safe deallocating

#define SAFE_DEL(a) {if(a){delele a;a = 0;}}

Solution

C/C++ Example 6 - STLclass Element

{

int ID;Created 0 addr 0xa719c0

d 1 dd 0 81 18

Command prompt


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164

;

public:

Element(int id)

{printf("Created %d at 0x%x\n", id, this);

ID = id;

}

~Element()

{

printf("Destroy %d at 0x%x\n", ID, this);

}};

int main()

{

list m_List;Element *e0 = new Element(0);Element *e1 = new Element(1);//add to list

m_List.push_back(e0); m_List.push_back(e1);//clear list

printf("-----Before clear-----\n");

m_List.clear();

printf("-----After clear-----\n");

return 0;

}

Created 1 addr 0xa81a18

-----Before clear-----

-----After clear-----

Memory

leak here

list

Item 0

Item 1

e0

e1

C/C++ Example 6 STL

( t )


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(cont.)

165

int main()

{

list m_List;

Element *e0 = new Element(0);

Element *e1 = new Element(1);

//add to list

m_List.push_back(e0);m_List.push_back(e1);

//clear list

printf("-----Before clear-----\n");list ::iterator i;for (i = m_List.begin(); i != m_List.end(); i++){

delete *i;}m_List.clear();

printf("-----After clear-----\n");

return 0;

}

Free data of each

element pointer

Created 0 addr 0xb61a28

Created 1 addr 0xb71a70

-----Before clear-----

Destroy 0 addr 0xb61a28

Destroy 1 addr 0xb71a70-----After clear-----

Command prompt

Example 7


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p

166

class CB {

public:

CB(){

m_iVal = 0;

}

~CB(){}

int m_iVal;

};

class CA {

public:

CA(){

m_pB = 0;

}

~CA(){

delete m_pB;

m_pB = 0;

}

CB *m_pB;

};

int main()

{

CB *B = new CB;

CA *A = new CA();

A->m_pB = B;

delete(A);

printf("%d", B->m_iVal);

}

B

Am_pB

Access violationreading location

.

Try toremove

delete m_pB

Example 7 (cont.)


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p ( )

167

class CB {

public:

CB(){

m_iVal = 0;

}

~CB(){}

int m_iVal;

};

class CA {

public:

CA(){

m_pB = 0;

}

~CA(){

delete m_pB;

m_pB = 0;

}

CB *m_pB;

};

int main()

{

CA *A = new CA();

A->m_pB = new CB()

delete(A);

}

Am_pB

Leak

Delete or not?

Use manual delocate m_pB

Solution

C/C++ Example 8


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class cA()

{

public :cA() {m_pdata = newint[100];}

virtual ~cA() {delete[]m_pdata;}

int *m_pdata;

};

class cB: public cA()

{

public

cB():cA() {m_pdata2 = new

int[100];}

~cB() {delete []m_pdata2;}

int *m_pdata2;

}

void main()

{

cA *A = new cB();

delete A;

}

Memory leak caused by

misunderstanding finalizationmethod

Without virtual, in this case,m_pdata is not deleted leak

Be careful with virtual for

finalization method

Solution

168

C/C++ Example 9


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/ p

Using new vs free. Nodestructor will be invokedafter free

169

class MyClass{

public

MyClass()

{

m_pdata2 = newint[100];

}~ MyClass()

{

delete []m_pdata2;

}

int *m_pdata2;

}

void main()

{

MyClass* p = new MyClass();

free(p);

}Leak here

What are reasons of memory

l k?


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leak?Forget/ misunderstand C/C++ mechanism

Out-of-Control (logic)

170

Current Solutions


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For Forget/ misunderstand C/C++ mechanism

Semi-automatic memory management

oReference Counting

Automatic memory managementoTracing Garbage Collection (GC): Java , C #

No GC mechanic for C/C++

171

Reference Counter: Good or bad ?


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Reference counter:Simple method formemory conflictresolution

Algorithms:

Increase counter whenuse as reference

Decrease when release

Delete memory ofcounter is zero

172

class IShareMem{

public:

IShareMem():m_iRefCounter(1){}

virtual ~IShareMem(){}

static

IShareMem* SetReference(IShareMem* src)

{

src->m_iRefCounter++;return src;

}

void Release()

{

m_iRefCounter--;

if (m_iRefCounter


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Good:

o Avoid conflict in memory usage. (See example no.7)

Bad:o Cause memory leak ifuser forget to release

o Hard to detect memory leak

o CAN NOT DETECT by tool

173

Current Solutions -

Disadvantage


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DisadvantageGarbage collectors generally can do nothing about

logical memory leaks

174

0

1

2

n

..

.

Alloc

Alloc

Alloc

Alloc

Which is really needed?A

B

D

E

Z

Do I alloc some-

where without

release?

Somethings else

is pointed

to an object

C/C++

How to avoid detect?


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How to avoid, detect?Rule:

o Remember to release dynamic data (pointer) HARD

o Keep our resource in well controlled TOO HARD

Detect

o By phenomenon on device ? not exactly

o By review source ? TOO HARD

o By tool

VC++ memory leak debugging

External toolo Cannot detect some cases.

175

C/C++

How to solve?


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How to solve?Easy to detect, but hard to solve

Depend on kind of memory leak

Experience

Organize source and keep it in control Such as a document about resource ?!?

176


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Detect Memory Leak

177

Memory leak quick detection


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0Windows: use task manager / process tab

0Android:adb shell top -m

See VSS, RSS

178

Use Visual studio supported

function


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functionUse __CrtDumpMemoryLeaks

Advantageo Easy to use

o Fully report about leak when application completed

o Free

Disadvantageo Cannot detect run-time

o Fail if application Crashed

Presentation:o Manually coding by user

o Use some lib such as VLD

179

Debug in Visual studio


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180

VLD Tool


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http://www.codeproject.com/KB/applications/visual

leakdetector.aspx

http://vld.codeplex.com/

Include vld.h in source

Add vld.lib

181

#include"vld.h"

#pragmacomment(lib, "vld.lib")

VLD Tool
http://www.codeproject.com/KB/applications/visualleakdetector.aspxhttp://www.codeproject.com/KB/applications/visualleakdetector.aspxhttp://vld.codeplex.com/http://vld.codeplex.com/http://vld.codeplex.com/http://www.codeproject.com/KB/applications/visualleakdetector.aspxhttp://www.codeproject.com/KB/applications/visualleakdetector.aspxhttp://www.codeproject.com/KB/applications/visualleakdetector.aspx


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0After finish application normally, memory leakinformation will be display in output

182

WARNING: Visual Leak Detector detected memory leaks!

---------- Block 3 at 0x006F4F98: 12 bytes ----------

Call Stack:

c:\users\ricky.ngk\desktop\testleak\testleak\main.cpp (81): TestLeak.exe!Init + 0x7 bytes

c:\users\ricky.ngk\desktop\testleak\testleak\main.cpp (108): TestLeak.exe!mainf:\dd\vctools\crt_bld\self_x86\crt\src\crtexe.c (586): TestLeak.exe!__tmainCRTStartup + 0x19 bytes

f:\dd\vctools\crt_bld\self_x86\crt\src\crtexe.c (403): TestLeak.exe!mainCRTStartup

0x76BBED6C (File and line number not available): kernel32.dll!BaseThreadInitThunk + 0x12 bytes

0x772237F5 (File and line number not available): ntdll.dll!RtlInitializeExceptionChain + 0xEF bytes

0x772237C8 (File and line number not available): ntdll.dll!RtlInitializeExceptionChain + 0xC2 bytes

Data:

74 A7 DF 00 01 00 00 00 20 60 6F 00 t....... .`o.....

0Double click the stack to navigate to source

Debug memory leak run-time


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Use some tool, such as:o Glow code: http://www.glowcode.com/

o Memory validator: http://www.softwareverify.com/cpp-memory.php

Advantage

o Runtime checkingo Nice Interface

Disadvantageo Not free

o Not easy to use. Need tutorial

Note: Those tool cannot working well with VLD

183

Outline
http://www.glowcode.com/http://www.softwareverify.com/cpp-memory.phphttp://www.softwareverify.com/cpp-memory.phphttp://www.softwareverify.com/cpp-memory.phphttp://www.softwareverify.com/cpp-memory.phphttp://www.glowcode.com/http://www.glowcode.com/


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Preparation

Getting Start

OOP

Memory management


Forward declaration


Template

Type casting

Exception handling

Endian

STL introduction

GNU GCC/G++ 184

Outline


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Preparation

Getting Start

OOP

Memory management


Forward declaration


Template

Type casting

Exception handling

Endian

Bit processing

STL introduction

GNU GCC/G++ 185

Forward declaration


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Declaration of a identifier which not completed

definition

For C/C++, aka function prototype (for function)

186

int first(int x) {

if (x == 0)

return 1;

return second(x-1);

}

int second(int x) {

if (x == 0)

return 0;

return first(x-1);

}

int second(int x);int first(int x) {

if (x == 0)

return 1;

return second(x-1);

}

int second(int x) {

if (x == 0)

return 0;

return first(x-1);

}

Forward declaration


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187

ClassA.h ClassB.h#ifndef _CLASSA_H_#define _CLASSA_H_

class ClassA{

public:

ClassA();

ClassB* m_pB;

};

#endif

#ifndef _CLASSB_H_

#define _CLASSB_H_

class ClassB{

public:

ClassB();

ClassA* m_pA;

};

#endif

ClassA.cpp ClassB.cpp#include "ClassA.h"

ClassA::ClassA(){}

#include "ClassB.h"

ClassB::ClassB(){}

Class forward declaration

#include "ClassB.h" #include "ClassA.h"

class ClassB; class ClassA;

Must be pointer

Outline


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Preparation

Getting Start

OOP

Memory management


Forward declaration


Template

Type casting

Exception handling

Endian

Bit processing

STL introduction

GNU GCC/G++ 188

Standard IO


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stdio.h

int printf ( const char * format, ... );

Format: %[flags][width][.precision][length]specifier

Write data to stdout and store

189

printf ("Characters: %c %c \n", 'a', 65);

printf ("Decimals: %d %ld\n", 1977, 650000L);

printf ("Preceding with blanks: %10d \n", 1977);

printf ("Preceding with zeros: %010d \n", 1977);

printf ("Some different radixes: %d %x %o %#x %#o \n", 100, 100, 100, 100, 100);

printf ("floats: %4.2f %+.0e %E \n", 3.1416, 3.1416, 3.1416);printf ("Width trick: %*d \n", 5, 10);

printf ("%s \n", "A string");

Standard IO


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stdio.h

int scanf( const char * format, ... );

Format: %[flags][width][.precision][length]specifier

Reads data from stdin and store

190

int n;

scanf ("%d",&n);

Standard IO


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std::cout

an object of class ostream that represents the standard

output stream

191

cout


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0

std::cin

an object of class istream that represents the standardinput stream

192

int input = 0;

cout > input;

cout


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193

FILE * fopen ( const char * filename, const char * mode ); Open file

int fclose ( FILE * stream ); Close a file

size_t fwrite ( const void * ptr, size_t size, size_t count,FILE * stream );

Write block of data to stream

size_t fread( void * ptr, size_t size, size_t count, FILE *stream );

Read a block data from stream

int fscanf ( FILE * stream, const char * format, ... ); Read formatted data from stream

int fprintf ( FILE * stream, const char * format, ... ); Write formatted output to stream

int fseek ( FILE * stream, long int offset, int origin ); Reposition stream position indicatorOrigin:

SEEK_SET : beginning of gfile

SEEK_END: end of file

SEEK_CUR: current position

long intftell ( FILE * stream ); Get current position in stream

void rewind( FILE * stream ); Set position indicator to the beginning

File
http://www.cplusplus.com/reference/clibrary/cstdio/fopen/http://www.cplusplus.com/reference/clibrary/cstdio/fopen/


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194

#include

int main ()

{

FILE * pFile;

pFile = fopen ("myfile.txt","w");

if (pFile!=NULL){

fprintf (pFile, "example");

fclose (pFile);

}

return 0;

}

Outline


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Preparation

Getting Start

OOP

Memory management


Forward declaration


Template

Type casting

Exception handling

Endian

STL introduction

GNU GCC/G++ 195

Function template


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special functions that can operate withgeneric types

Can be adapted to more than one type or class

without repeating code

A set of needed functions will be created whencompile slow down compiling process

196

template function_declaration;

template function_declaration;

Function template

Example 1


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Example 1

197

template T GetMax (T a, T b)

{

return (a>b?a:b);

}

int main ()

{int i=5, j=6, k;

long l=10, m=5, n;

k=GetMax(i,j);

n=GetMax(l,m);

cout


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Example 2

198

template U GetMax (U a, V b)

{

return (a>b?a:b);

}

int main()

{

cout


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A class can have members that use template

parameters as types

199

template

class mypair

{T values [2];

public:

mypair (T first, T second)

{

values[0]=first; values[1]=second;

}

};

int main(){

return 1;

mypair Pair1(100, 200);

mypair Pair2('A', 'B');

}

Class template


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template class mypair

{

T a, b;

public:

mypair (T first, T second) {a=first; b=second;}T getmax ();

};

template T mypair::getmax ()

{

T retval;

retval = a>b? a : b;

return retval;

}

int main ()

{

mypair myobject (100, 75);

cout


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Template specializationDefine a different implementation for a template

when a specific type is passed as template parameter

201

// class template:

template

class mycontainer{

T element;

public:

mycontainer (T arg)

{

element=arg;

}

T increase () {return ++element;}};

// class template specialization:

template

class mycontainer {

char element;

public:

mycontainer (char arg)

{

element=arg;

}

char uppercase (){

if ((element>='a')&&(element


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New code will be generated while compiling, DO NOT

split a template class into two parts: .h, and .cpp

Easy to use, but not easy to debug/read

202

Mixin


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We can implement inheritance delaying the definition

of the base.

203

template

class Mixin : public Base {};

class Base {};

Mixin issue


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If the client never calls Todo there is no errormessage!

204

template

class Mixin : public Base

{

public:

void Todo() {Base::Do();}};

class Base

{};

C++ meta programming


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Is writing programs that represent and manipulate

other programs (e.g. compilers, program generators,

interpreters) or themselves (reflection).

In C++, meta programming base on: Template

205

Example: Factorial


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N! = 1 x 2 x 3 x x N

206

template struct Factorial

{

enum {RET=Factorial::RET*n};

};

// Note: template specializationtemplate struct Factorial

{

enum{RET=1};

};

int main(){

printf("%d", Factorial::RET);

return 1;

}

Outline


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Preparation

Getting Start

OOP

Memory management


Forward declaration


Template

Type casting

Exception handling

Endian

STL introduction

GNU GCC/G++ 207

Type casting


208/245

0Convert from specific type to another type

char a = 10;

int b = (int) a;

bool c = a;

gettingstartedcpp - full.pdf

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