C_ProgrammingPart 2

ENG. KEROLES SHENOUDA

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Features of C

- Simple, versatile, general purpose language- Programs are fast and efficient- Has got rich set of operators- more general and has no restrictions- can easily manipulates with bits, bytes and addresses- Varieties of data types are available- separate compilation of functions is possible and such functions can be called by any C program- block-structured language- Can be applied in System programming areas like operating systems, compilers & Interpreters, Assemblers etc.,

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Variable Name 4

Comments

Sometimes programmers need to add some notes beside their code. Those notes are veryimportant to describe the code and to clarify complex operation. Notes or comments can beadded in two ways as shown in the following example.

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Data Types 6

Primitive/Basic TypesDerived

User Defined

enum typedef

Arrays

structure union

pointer Integer ValuesReal Values

signedunsigned

Integer Values 7

long long 8 –9,223,372,036,854,775,808 to 9,223,372,036,854,775,807

unsigned long long 8 0 to 18,446,744,073,709,551,615

Unsigned Integer

0 >>> (2 -1)size_in_bits

Signed Integer

-(2)(size_in_bits-1)

>>> +(2 -1)(size_in_bits-1)

For example “char” 8

For example if the Unsigned charvalue uses one byte (8 bits) to

hold the numeric value:

Another example if the Signed char value uses one byte (8 bits)

to hold the numeric

value. If Tow‟s Complement method is used to represent the

negative values:

For example “char” 9

For example if the Unsigned short value uses one byte (16 bits)

to hold the numeric value:

Another example if the Signed Integer value uses four byte (32 bits) to hold the numericvalue. If Tow‟s Complement method is used to represent the negative values:

Note

int, this data type called the machine dependent data type, which means its

size and rangevary from a machine type to another machine type (EX: in 8 bit computers intis 1 byte, in16 bit computers int is 2 bytes, in 32 bit computers int is 4 bytes, in 64 bit computers int is 8bytes).Know that (32 Bits computers) means the principle data unit size in those computers are 32bit, which mean the computer is designed and optimized to process 32 bit values

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Floating-Point Types

Type Storage size Value range Precision

float 4 byte 1.2E-38 to 3.4E+38

6 decimal places

double 8 byte 2.3E-308 to 1.7E+308

15 decimal places

long double 10 byte 3.4E-4932 to 1.1E+4932

19 decimal places

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IEEE-754 32-bit Single-Precision Floating-Point Numbers

In 32-bit single-precision floating-point representation:

The most significant bit is the sign bit (S), with 0 for positive numbers and 1 for negative numbers.

The following 8 bits represent exponent (E).

The remaining 23 bits represents fraction (F).

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Example 1: Suppose that IEEE-754 32-bit floating-point representation pattern is 0 10000000 110 0000 0000 0000 0000 0000.

Sign bit S = 0 ⇒ positive number

E = 1000 0000B = 128D (in normalized form)

Fraction is 1.11B (with an implicit leading 1) = 1 + 1×2^-1 + 1×2^-2 = 1.75D

The number is +1.75 × 2^(128-127) = +3.5D

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Example 2: Suppose that IEEE-754 32-bit floating-point representation pattern is 1 01111110 100 0000 0000 0000 0000 0000.

Sign bit S = 1 ⇒ negative number

E = 0111 1110B = 126D (in normalized form)

Fraction is 1.1B (with an implicit leading 1) = 1 + 2^-1 = 1.5D

The number is -1.5 × 2^(126-127) = -0.75D

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2′s Complement 15

C Programming Input Output (I/O): printf() and scanf()

C programming has several in-built library functions to perform input and output tasks.

Two commonly used functions for I/O (Input/Output) are printf() and scanf().

The scanf() function reads formatted input from standard input (keyboard) whereas the printf() function sends formatted output to the standard output (screen).

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Input Output 17

Eclipse's terminal emulator issue with scanf()

Eclipse's terminal emulator might be different and do more buffering. Try calling fflush(stdout); between the printout and the call to scanf().

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C Floats Input/Output 19

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

%10s%-10s.4s

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writes a single character.writes a single character.converts a signed integer into decimal

converts a unsigned integer into octal representationconverts an unsigned integer into hexadecimal representation

converts an unsigned integer into decimal representationconverts floating-point number to the decimal notation

converts floating-point number to the decimal “Scientific”converts floating-point number to"Special valuesTake from , …..Shift 10-string’s length places then print the stringPrint the string then shift to 10-string’s length places Print only 4 char from string

int printf( const char* format, ... ); 21

Quiz 22

Quiz 23

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PrintfTricks

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Solution 27

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Data Conversion and Type Casting 29

Data Conversion and Type Casting 30

Data Conversion and Type Casting 31

The conversion from larger to smaller data types may lead to some data losses. For thatreason the compiler warns you against this type of operation. However sometimes theconversion does not affect the data like the second expression (b = y). Compiler is not able todifferentiate between safe or unsafe situation, for that reason you must use the type castingto force the conversion if you decide that it is safe.

Mathematical and Logical Expressions 32

Mathematical and Logical Expressions 33

Mathematical and Logical Expressions 34

Coding Convention

Coding convention is a set of rules that enhance the readability and the understandability ofthe code. At the end of each chapter a list of standard and related coding convention ismentioned.

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Coding Convention 36

Generally following roles must be obeyed towrite an arranged code.

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Follow Chapter 2: Controlling Program FlowC PROGRAMMING FOR ENGINEERS, DR. MOHAMED SOBH

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References 39

The Case for Learning C as Your First Programming Language

A Tutorial on Data Representation

std::printf, std::fprintf, std::sprintf, std::snprintf…..

C Programming for Engineers, Dr. Mohamed Sobh