c++

University of South Asia, Lahore

1Lecturer: Engr. Tariq Sadiq

Today’s Menu History of C++.

Writing C++ Program.

Structure of C++ Program.

C++ Statements.

Keywords.

Tokens.

Variables and rules for writing variables names.

Data Types in C++.

Declaration of variables.

Initialization of variables.

Constants.

Arithmetic Operates.

Arithmetic Expressions.

Order of Precedence of Operators.2Lecturer: Engr. Tariq Sadiq

Introduction C plus plus is a powerful computer language.

Advance version of C language.

C is a procedural language (e.g. get some input, add these numbers, divide by 6, display the output)

C++ is a object-oriented programming.

Brief History In 1967 BCPL was developed by Martin Richards.

In 1969 B language was developed by Ken Thomson.

Both B and BCPL were type-less languages.

In 1972 C language was developed by Dennis Ritche. (data type)

In early 1980’s C++ language was developed by Bjarne(Unix systems)


Writing C++ Program Different compliers (Turbo C++, Borland C++, Dev-C++)

First.cpp, First.obj, First.exe

Structure of C++ ProgramPreprocessor Directives (The instructions that are given to the complier before the beginning of any program)

Header File (is a C++ source code that contains the definition of functions/objects presents in library)

The main() Function (indicates the beginning of C++ program)

Example:

#include <iostream.h>

main()

{ cout<<“This is my First Program”;

}4Lecturer: Engr. Tariq Sadiq

C++ Statements

main()

{

program statements……

}

Key Words The words that are used by the language for special purposes are called

as keywords (i.e. reserved words)

These words cant be used as variable names in a program.

Example:

Include, main, int


Tokens In C++ the elements of a statement are called tokens

Example:


main()

{ int a, b, c;

}

Variables A quantity whose value may change during the execution of program is

called as variable.

Rules for writing variable

names6Lecturer: Engr. Tariq Sadiq

The first character of variable name must be alphabetic character.

Underscore can be used as first character of variable name.

Special characters, such as arithmetic operators, #,^, cant be used in variable name.

Reserved words cant be used as variable names.

A variable name used for one data type cant be used for another data type

C++ is case sensitive language so Pay and pay are two different variables.

Some examples of the valid and invalid variable names are given as:


Variable Name Valid/Invalid Remarks

Hassan valid

perform valid

double invalid C++ reserved word

foxpro valid

switch invalid C++ reserved word

Tania valid

int invalid C++ reserved word

3taq invalid Starts with numeric

unsigned invalid C++ reserved word

x-y invalid Special character not allowed

Taq Ahd invalid Space is not allowed

Lecturer: Engr. Tariq Sadiq 8

Data Types in C++ int

(The int represents the integer data)

float

(The float represents the real or floating type data)

double

(The double represents the real or floating type data)

Char

(The char is used to declare character type variables)

Bool

(Boolean is used to represent true or false)


Declaration of variables Assigning the name and data type that a variable can hold is called

declaration of the variable.

type list of variables;

Example:

int a, xy;

float b;

char nm [15];

double sum;

Initialization of Variables Assigning a known value to a variable at the time of its declaration is

called as initialization of the variable. (int a=4, b=1997)



Example:


#include <conio.h>

main ()

{

int a=2,b=3;

float p=3.14;

char name[8]=“tariq”;

cout<<a<<endl;

cout<<b<<endl;

cout<<p<<endl;

cout<<name<<endl;

getch();

}

Constants A quantity that cant change its value during execution of program.

Integer constants

A numerical value without a decimal part is called integer constants.

Example:

cout<<1234;

cout<< 176;

Floating point constants

Numeric value that have an integer as well as a decimal part are called floating-point values.

Example:

123.5E2

Character constants

A single character enclosed in single quotation marks is called character constant.


Example:

‘a’ , ‘/’ , ‘+’

String constants

A sequence of characters consisting of alphabets, digits and/or special characters enclosed in double quotation marks is called string constant

Example:

“Pakistan” , “Lahore-54500”

Const QualifierThe data item that follows the keyword “const” cant change its valude

during execution of the program.

Example:



#include <conio.h>

main ()

{

int r=2;

Const float p=3.14;

float peri;

peri=2*p*r;

cout<<“Result is=“<<peri;

getch();

}


The “define” Directive It is preprocessor directive. It is used to define a constant quantity. It is

used at the beginning of the program.

#define identifier constant

Example:


#define p 3.14

main ()

{

int r=2;

float peri;

peri=2*p*r;

cout<<“Result is=“<<peri;

getch();

}

Lecturer: Engr. Tariq Sadiq17

Arithmetic OperatorsOperator Meaning

+ Addition

- Subtraction

* Multiplication

/ Division

% For remaninder



main ()

{

int sum,subtract,multiplication,division,remainder;

sum=5+2;

Subtract=5-2;

Multiplication=5*2;

Division=5/2;

Remainder=5%2;

Cout<<“Addition of 5&2 is=“<<sum<<endl;

Cout<<“Subtraction of 5&2 is=“<<subtraction<<endl;

Cout<<“Multiplication of 5&2 is=“<<multiplication<<endl;

Cout<<“Divison of 5&2 is=“<<divison<<endl;

Cout<<“Remainder of 5/2 is=“<<remainder<<endl;

getch();

}


Arithmetic ExpressionIf m=10, x=5

res=m*x+100

Order of Precedence of Operation All multiplications and divisions are performed first from left to right.

All additions and subtractions are then performed from left to right.

If parentheses are used in an expression, the expression within parentheses are first computed from left to right.

When parentheses are used within parentheses, the expression within innermost parentheses is evaluated first.

Example:

(4-(3*5))+2


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