c programming language.pdf

8/14/2019 C Programming language.pdf

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C Programming language

Section 1


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Program: is a set of statements that solves a problemAll programs work on data, which is the fuel of the program.

So, we will learn the types of data, how to deal with them, andthe different arrangement of data

The program itself is trying to solve a real world problem. So,

we have:

Real World Computer World

This is the problem The Program

The transformation from the real world to the computer world

is an industry called programming


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Why Learn C?

Compact, fast, and powerful

Mid-level Language

Standard for program development (wide acceptance) It is everywhere! (portable) Supports modular programming style

Useful for all applications

C is the native language of UNIX

Easy to interface with system devices/assembly routines C is terse


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The following program is written in the C programming

language:

#include int main(){printf("Hello World \n");

}


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The Preprocessor :The preprocessor are compiler directive to direct the

compiler before compiling.

The preprocessor statements are statements that execute

before compiling This statement begin with # example:

#include

The header files are file that contain the function prototype

of the function defined in the library file.

Before compilation, the compiler will compile the header

file then complete the program.


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The data type:Char (1byte) (-128 to 127)

int (2byte) (-32768 to 32767)

float (4byte) (3.4e-38 to 3.4e38)

double (8byte) (1.7e-308 to 1.7e308)

The difference between float and double is inthe precision The float has 7 number after the

decimal point The double has 15 number after

the decimal point.


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There is also short int (2byte)

long int (4byte) (-2147483648 to 2147483647)

long double (10byte) 23 number after the decimal point

unsigned int (2bytes) (0 to 65535)

unsigned short int (2bytes) (0 to 65535)

unsigned long int (4bytes) (0 to 4294967295


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Constant:It is a fixed value that the program may not change. It can have any

of the data type above.

It is declared with one of the two ways:-In the preprocessor:

# define constant-name constant-value

Ex: - # define x 3 this mean x is an integer with value 3

# define ch a this mean ch is a character with value a

-In the program

const data-type constant-name = constant-value;

Ex:- const int x=3;

const char ch=a;


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Note1. The variable may be declared:

Locally: It is declared in the function. So, we can use it only in this

function and it end with the end of function.

Global: The variables are declared out of any function. So, we can

use them in any part of the program and also we can use them in any

function2. Any variable declared in the main () are locally for

the main only.

3. It is not recommended to use global variable.


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The program statementsThe program statement consists of many things:

Input function, Expression and operation, Output functionEach statement must terminate with ;


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The input function:These function are used to get data from users.

The following function can be used: scanf() function:it has the format:

scanf(format specifier, &var-name);

example: scanf(%d,&x);

it is in the header file stdio.h


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Format specifier:%d integer

%f float

%c char

%s string%u unsigned integer

%x hexadecimal

%ld long integer

%lf double

%Lf long double


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The output function:These functions are used to display the results on the screen.

The following function can be used:

printf() function:It has the format: printf(message sequence, variable);

Example: printf(hello %c\n,ch);It is in the header file stdio.h

putchar() function:it display a character on the screen

it has the format: putchar(int );

example: putchar(23);

It is in the header file stdio.h


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The Expression and Operators:1 OperatorsThere are several operators in C language:It may be unary operator which has one operand or binary

operator which has two operands. All operation must have a

value.

The operator may be classified as:The Mathematical operator:+ sign add the two operands

- sign subtract the second operands from the first operands

* sign multiply the two operands

/...sign divided the first operand by the second

%.sign modulus operator (it give the reminder of the division)

E l


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Example:

# include

void main()

{int i,x,y;

x=100;

y=7425;

i=y%x;

printf(%d,i);}

The value will be 25

Note:*) In the division, if we divide int by int the result will be integer.

*) To divide two integer and to have the value float we must make one of the operandsacts as float. This is done by using type casting:

The type casting: You force an expression to be of a specific type during a certainstatement only. It has the form: (new_type) expression so we can use it to have a decimal

value when dividing two integer


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Example:

# include

int main()

{

float x,y;

float i;

x=3;

y=7;

i=y/x;

printf(%f,i);

return 0;

}

The value of i will be 2.3333333


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The Relational operator

It allows the programmer to compare two values and return non zero

value if the comparison is right or zero if the comparison is wrong.

Usually used for conditional statements.

> greater than

< lower than

>= greater than or equal


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The Increment/Decrement operator

++ increment by 1-- decrement by 1

The pre-increment: ++x

The post-increment: x++The difference between pre-increment and post-

increment can be seen in

the following examples


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#include

void main()

{

int x,y;x=10;

y=++x;

printf(%d \n,x);

printf(%d \n,y);}

the value of x=11

the value of y=11

x=x+1;

y=x;

increment then assigning


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#include

void main()

{

int x,y;x=10;

y=x++;

printf(%d \n,x);

printf(%d \n,y);}

the value of x=11

the value of y=10

y=x;

x=x+1;

assign then increment


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The assignment operator= equal x = 5;

+= x += 5; equivalent to x = x+5;-= x -= 5; equivalent to x = x-5;

*= x *= 5; equivalent to x = x*5;

/= x /= 5; equivalent to x = x/5;

%= x %= 5; equivalent to x = x%5;Note:

The assignment puts the value at the Right Hand Side(RHS) in the variable at the Left Hand Side (LHS).

Then the operation of the assignment has a value whichis the RHS. This helps us to perform multiple

assignment which is valid in C Language.

i.e. : x = y = z = 4;


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2 ExpressionA) Selection (conditional) statements

1 The if statements:if (condition)

{

statements;

}The statement between { } will be valid if the condition is true(non

zero) other wise it will be escaped and continue the program.

The if statement is used when some extra instruction will be done if

the condition is valid then continues the program and if thecondition is not valid, it continues the program:


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3)The Switch case:

It is a multiple branch selection, it has the form:

switch (expression)

{

case constant1:

{

statement; break;

}

case constant2:

{

statement; break;

}

default:

{statement;}

}


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Example1:Write a program to enter 1, 2, or 3 then the program

write one, two or three otherwise write Out of range

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