Notes C Language

7/31/2019 Notes C Language

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C. Programming Language:

Programming: A Computer can do anything but; about itself it can do nothing. It must be giveninstruction about the work which is to be done by the computer. The process of giving instructions to the

computer to get our work done is known as Programming. Such a list of Instructions given to thecomputer is known as Program.

Language:A set of Rules and Symbols used for communication between two things are known as Language. We can

classify the languages in following four categories:

1. Human Language: This is a Language which is understandable and used by humans for

communication(Conversation). e.g. English, Hindi. Punjabi.

2. Machine Language:This language is used by Machine (Computer) for its Internal Processing.All the parts of a Machine use this language to transfer information from one place to another. E.g. Binary

Language.3. Programming Language: This language is understandable by the human but the instructionwritten in Programming language can be converted into Machine Language also. This is the main use of

Programming Language as it is used to create an interface for instruction between computer and a Human.

This language is very similar to the human language due to which it is very easy to understand. This

language is used to design application softwares. Compiler and interpreters are used to convert the

instructions from programming language to Machine language. E.g. C,C++, Java, VB etc

4. Assembly Language: This language do the same as programming language does but the onlydifference is that language is more closer to the machine language. This language use some symbols for

instructions representation. Due to which this language is very difficult to be learnt for programmer. This

language is used to design System soft wares. Assembler is used to convert the instructions from assemblylanguage to Machine language. E.g. Assembly Language.

Character SetCharacter Set means that the characters and symbols that a Langauge can understand and accept. C

Language is having expressions,words,c-statement and other elements as a tokens. Character set is the

combination of alphabets or character,digits ,special symbols and white spaces.

Tokens of C Language:Variable:Computer require memory location to store any data or value. Each location used to store datamust be declared first before its used. A memory location reserved to store some data are known as

variable. The value stored within a variable can be changed for any no of times:

Constant:These are some symbols used to represent a value. A Variable can store the value in the formof a constant. We can say, everything which is stored in the variable is constant. These are also known as

Literals. The value of the constants remain unchanged forever.

We can classify constants as the hierarchy given below:

Constant

Numeric Character

Integer Real or Float Single Character String Backslash Character

Signed Unsigned Signed Unsigned


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Identifiers:Each Reserved location must be identified with a unique name. This identification symbolis known as Identifier. We can say An identifier is a name of Variable given on the time of its

declaration.

Rollno

Variable

Keywords:Each language is having some reserved words which are having their pre defined meaning which are not

changeable. These kind of reserved words are known are Keywords. C language is having 32 keywords.

Such as int, char, do, while, if, switch, for, long. etc..

Data Types:These are keywords which are used to let the computer know about what type of data is to be stored in a

variable. We can say All those keywords are Data Types which are used to represent the Type of Data

within a computer Language. Such as int, char, float

The Hierarchy of Data Types is as under:

Data Type

Scalar Derived User Defined Void

Structure Union Enumerators

Array String

Integer Float Double Character

101Constant

Identifier


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Scalar Data Type

Sr.

No

Description Keyword Size(In

byte)

Range Conversion

String1 All integers

Nos without decimal

points

int 2 -32768 to

32767

%d

2 All Floats

Nos with decimal

points too

float 4 -32768 to

32767

%f

3 Alphanumeric char 1 256 %c

4. Extended range of

Integers

long int 4 231 %ld

5. Extended range of

Floats

double 8 2308 %lf

Operators:An Operator is a special symbols that specifies what operation is perfomed mathematical exppressions In

C Language operator can be either unary ,binary or ternary. These are symbols which are used to represent

operations on one, two or three operands. We can classify the operands in following three categories:

Unary operators:All those operators which are applied on one operand (variable) are known as Unary Operators

Such as

a. Increment Operator (++)

b. Decrement Operator(--)

Increment operator increase the value of the operand by one. Such as

a++ means that a=a+1e.g.

a=1;

a++;

now a will be 2

likewise decrement decrease the value of the operand by one. Such as

a- - means that a=a-1;

Binary Operators:All those operators which are applied on two operand are known as Binary Operators

like as a+b

a. Arithmetic OperatorsThe Arithmetic operators are used for mathematical calculations. The arithmetic operators are

binary operators that work on the built-in data type eg. int char & float. Here are the most common

arithmetic operators

+ Additional Operator

Subtraction Operator

/ Division

* Multiplication

% (remainder After Division)

b. Relational Operators


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Relation operators are used to check relation between two Variables. In Other words, the

operators used to make comparisons between two variables are called Relational operators. The

result of a relational operation is a Boolean value that can only be true or false, according to its

Boolean result. We may want to compare two expressions, for example, to know if they are equal

or if one is greater than the other is. Here is a list of the relational that can be used in C Language

a. < Less Thanb. > Greater Thanc. = Greater than equal to

e. = = Equal to

f. != Not equal to

c. Logical OperatorsThe logical operators && and || are used Combine one or more expressions to obtain a single

relational result. The operator && corresponds with Boolean logical operation AND. This

operation results true if all Conditions are true, and otherwise false. The following table shows the

result of operator && evaluating the expression a && b:

a. && (And)

b. || (Or)

c. ! (Not)

And: It will be true only when all conditions are true. If one of the condition is false, it will be

false

Or: It will be false only when all conditions are false. If one of the condition is true, it will be

true.

Not: It will generate the compliment of the condition. i.e. it will be true if the condition is false

or Vice-Versa.

d. Assignment Operatorsa. += Submission Assignment.

b. -= Subtraction Assignment.

c. /= Division Assignment.

d. *= Multiplication Assignment.

e. %= Modulation Assignment.

Such as:

A+=5; means that

A=A+5; and so on for other operators.....

c. Ternary Operators(Conditional operator)All those operators which are applied on three operand are known as Ternary Operators

Such as

?

:Syntax()? :;

Such as

A=4;

(A


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Variable:Computer require memory location to store any data or value. Each location used to store data must be

declared first before its used. A memory location reserved to store some data are known as variable. The

value stored within a variable can be changed for any no of times:

Syntax for Declaring a Variable:

data type variable Name;

Such as

int Rollno ;

it means Rollno is a variable which is of integer data type;

Naming conventions (Rules) for Variables:1. A variable name should be short, meaningful and must be without blank space.

2. No Two variables can have same name.

3. No keyword can be used as a variable name.

4. No special Symbol other than Underscore ( _ ) can be used within a variable name.

5. Variable names are case sensitive.

6. Variable name must begin with an alphabet or ( _ ).There are two type of variables :

Local Variable

Global Variable

Local Variables

A local variable is a variable that is given local scope. Such a variable is accessible only from thefunction

orblockin which it is declared. Local variables are declared within the body of a function

Global Variable

A global variable declaration looks normal, but is located outside any of the program's functions. This is

usually done at the beginning of the program file, but after preprocessor directives. The variable is not

declared again in the body of the functions which access it. Global and external variables can be of any

legal type. They can be initialized, but the initialization takes place when the program starts up, before

entry to the main function.

Components of Program.

1. Comment Entry: This is a Short summary of Program. We can write anything in simpleenglish at any place within a program and every comment will be ignored by the compiler duringcompilation.

Syntax:// Single line comment.

/* Multiple

Lines

As

A Comment */

2. Sentence : Each line of a program is a sentence:

3. Sentence Terminator : This symbol is used to mark the end of each sentence. The symbol

used for this purpose is Semi column ( ; ).4. Delimiters : These Symbols are used to mark a block within a program. Each program start and end

with a Delimiter.

Symbols used are:
http://en.wikipedia.org/wiki/Variablehttp://en.wikipedia.org/wiki/Scope_(programming)http://en.wikipedia.org/wiki/Subroutinehttp://en.wikipedia.org/wiki/Subroutinehttp://en.wikipedia.org/wiki/Statement_blockhttp://en.wikipedia.org/wiki/Scope_(programming)http://en.wikipedia.org/wiki/Subroutinehttp://en.wikipedia.org/wiki/Statement_blockhttp://en.wikipedia.org/wiki/Variable


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{ Start of Block

} End of Block.

5. Program name : This is an identification symbol for each of our file. Each file must have a unique

name and must have .c as an extension . Such as

Myfile.c

programe.cInput Function:These functions are used to read data from the input device like keyboard. There is a wide range of input

functions in C language. Some of them are listed bellow.

1. getch();

This input function read a character from the keyboard. This function neither display the input character

nor echo the screen. i.e. no enter key is required to be pressed when the char is entered. As:

char a;

a=getch();

2. getche();

This input function read a character from the keyboard. This function not display the input character butecho the screen. i.e. Enter key is required to be pressed when the char is entered. As:

char a;

a=getche();

3. getchar();This input function read a character from the keyboard. This function display the input character and echo

the screen. i.e. Enter key is required to be pressed when the char is entered. As:

char a;

a=getchar();

4. scanf();This input function is widely used for input of data as it can read any type of data from keyboard. User

required to specify the data type of the variable in which we have to store data. The syntax for using this

function is as under:

scanf(Conversion String,&name of Variable);

e.g.

int x;

scanf(%d,&x);

Output Function:These functions are used to print any value to the output device as like Monitor. This function can

print the value of any type with the help of conversion string. We can display a simple message to the

output screen also using printf() function. The syntax for using this input function is as under.

1. printf();printf([] [],);

e.g.

int x;

x=10;

printf(x= %d,x);

Output:

x=10

Layout of A C Programe:


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main()

{

- - - - -

Declaration block:

- - - - -

- - - - -

- Operation Block

- - - - -

- - - -

}

e.g;

Write a program to find the sum of two nos:#include

Void main()

{

int a,b,c;

printf(Enter any No :);

scanf(%d,&a);printf(Enter another No :);

scanf(%d,&b);

c=a+b;

printf(The Sum is : %d,c);

}

Output:

Enter any No : 10

Enter another No : 20 The Sum is : 30

Control Statements

A program consists of a number of statements which are usually executed in sequence. Programs can be

much more powerful if we can control the order in which statements are run. The following are the Control

Statements supported by the C language.

If Statement

If-else Statement

Switch Statement


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Goto statement

If statement :The simplest form of the control statement is the If statement. It is very frequently

used in decision making and allowing the flow of program execution.

The if statement is the most simple and powerful decision control statement which is used to control the

sequence of execution of statements. It is used to execute a block of statements according to the condition,If the condition is true then the block of statements will be execute otherwise not execute.

The syntax of if statement is shown as following.

If(Condition)

Statement 1;

Statement 2;

N

}

Exp.

If(marks>34)

{

printf( pass );

}

The if else Statement

In the case of if statement ,the block of statements are executed only when the condition is true. Otherwise

the control is transferred to the next statement following the if block.

In ifelse statement, If the condition is true then the if block will be execute otherwise else block

will be execute. The syntax of if-else statement is shown as following.

Syntax:

If(Condition)

{

Statement 1;

Statement 2;

}

else

{

Statement 1;

Statement 2;

}

Exp.

if (result >= 45)

{printf("Pass");

}else{

printf("Fail");


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}

If we wish to have more than one statement following the if or the else, they should be grouped together

between curly brackets. Such a grouping is called a compound statement or a block.

if (result >= 45){ printf("Passed\n");

printf("Congratulations\n")}

else{ printf("Failed\n");

printf("Good luck in the resits\n");}

Nested if-else statement:

When we use if statement within the another if block or else block. This concept is known as nested if-else

statement. The different ways for representing nested if-else statement are:

If(Condition1)

{

If(Condition2)

{

Statement 1;

Statement 2;

}

}

else

{If(Condition3)

{

Statement 1;

Statement 2;

}

}

The 2nd syntax of nested if-else statement is also known as ladder if else statement.

The if statement may be nested as deeply as you need to nest it. One block of code will only be executed if

two conditions are true. Condition 1 is tested first and then condition 2 is tested. The second if condition is

nested in the first. The second if condition is tested only when the first condition is true else the program

flow will skip to the corresponding else statement

Switch StatementThe switch statement is a multi decision making statement. Which Select one of alternate from

several alternatives based on the value of condition or expression, If we have a large decision tree and all

the decisions are depend on the condition variable. The switch statement tests the value of given variable

against a list of case values. When a match a found, a block of statements are executed according to case.

The break statement is used at the end of each case block. when it executed then the control

transfer from switch statement. The default is an optional case. It will be executed if the value of

condition(expression) does not match with any case values.

The syntax of switch statement is shown as following

Syntax:

If(Condition1)

{

Statement1;

Statement2;

}

else

{

if(Condition2)

{

Statement1;Statement2;

}

}


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Each case is normally terminated with a break statement. When a break statement is execute the

program comes out the switch statement.

If the switch statement is false then default statement will be execute.

switch(condition)

{

case 0 :

statemet1;

statement2;

break;

case 1 :

statemet1;

statement2;

break;

case 2 :

statemet1;

statement2;

break;

default :

statement;

break;

}

Branching

The C Programming language programs presented until now follows a sequential form of execution of

statements. Many times it is required to move(alter) the flow of the sequence of instructions. C language

provides statements that can alter(move) the flow of a sequence of instructions. These statements are called

Branching control statements. These Branching statements help to jump from one part of the program to

another. The control transfer may be conditional or unconditional. Exp: goto statement

goto Statement:

The goto statement is an unconditional control statement that jump the control to a different

location in the program without checking any condition.

Syntax:

goto Label;

Statement 1;

Statement 2;

Label :Statement 1;

Statement 2;

Continue statement:

The break takes out of the loop when it is executed. But continue statement is execute the statement

continually if the condition become false. It go back to the top of the loop. and the continue statement tells

the compiler to skip the following statement The syntax of continue statement is shown as following:

Syntax:Continue;

LOOP


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A loop is a series of commands that will continue to repeat over and over again untill a condition is met.

For example, loop is the process of execution of block of statement in program according to the condition

In C programming language three types of loops are used:

While Loop

Do-while Loop

For loopThese above loops follow the necessary three steps:

Initialization;

Condition

Increment/Decrement;

While loop:While loop is the most common usable loop it is used forrepeating a statement until the condition becomea false. The body of while loop statements are execute according to the condition .if the condition is true

then the statements are execute otherwise not execute. So that the compiler first check the condition . The

syntax of while statement is shown as following :Syntax:

Initialization ;

While(condition)

{

Statement1 ;

Statement2 ;

|

|

N ;

Increment/Decrement;}

The do while Loop

In a do-while loop, the test expression is evaluated at the beginning of the loop. This is very similar to the

while loop except that the test occurs at the end of the loop body. This guarantees that the loop is executed

at least once time whether the condition is true or false. The test then verifies the condition, and loops back

to read again if it was unacceptable

Syntax.

Initialization ;

do

{

Statement1 ;

Statement2 ;

|

|

N ;

Increment/Decreament;

}

While(condition);

For loop


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The for loop is a easy loop because This loops use the three necessary steps in single line separated by

semicolons.

The first is run before the loop is entered. This is usually the initialization of the loop variable.

The second is a test condition , the loop is exited when condition become false.

The third is a statement to be run every time the loop body is completed. This is usually anincrement of the loop counter.

Syntax of for loop is shown as following :

for(initialization; condition; increament/decreament)

{

Statement1;

Statement 2;

Statement 3;

}

Nested Loops

When we use a loop within another loop this concept is know as nested loop. The first loop in nested loop

know as outer loop and another loop is know as inner loop. The controller firstly check the outer loop if

the outer loop is true than the inner loop will be execute otherwise not execute. It means inner loop isalways depend on the outer loop . The syntax of nested loop (using while loop) is

Initialization;

While(condition)

{

Initialization;

While(condition)

{

Statement1;

Statement2;

||

N


}


}

Array:

An array is a series of elements ( variable) of the same data type which placed in contiguous memorylocations that can be individually referenced by adding an index to a unique number. for example, we want

to store 5 values of type int in an array without having to declare 5 different variables, each one with a

different identifier. Instead of that, using an array we can store 5 different values of in an array

Outer loop

Inner loop


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Suppose we want to store 10 students roll_no for this, we have two options :

we can declare 10 different different variables and each variable can store 10 students roll_no

we can declare only one variable which can hold 10 students roll_no. this variable is know as

array variable

For example, an array to contain 5 integer values of datatype int called billy could be represented like this:

where each blank box represents an element(variable) of the array, that in this case are integer values of

type int. These elements are numbered from 0 to 4 since in arrays the first index is always 0, independently

of its length . Like a regular variable, an array must be declared before it is used. A typical declaration for

an array in C language is:

data type ArrayName [Size of array];

where type is a valid datatype (like int, float...), name is a valid identifier and the size(elements) field

(which is always enclosed in square brackets []), specifies how many of these elements the array has to

contain.

Therefore, in order to declare an array called billy as the one shown in the above diagram it is as simple as:

Int billy[5];

There are three types of array:

1. One dimension array(1D array)

2. Two dimension array(2D array)

3. Three dimension array(multiple array)

Initializing of An one dimension Arrays.when we declare an array, we have the possibility to assign initial values to each one of its elements byenclosing the values in braces { }. For example:

int billy[5] = { 16, 2, 77, 40, 12071 };

This declaration would have created an array like this:

The amount of values between braces { } must not be larger than the number of size of array that we

declare for the array between square brackets [ ]. When an initialization of values is provided for an

array, C allows the possibility of leaving the square brackets empty []

Accessing the values of an array.

In any point of a program in which an array is visible, we can access the value of any of its elements

individually as if it was a normal variable, thus being able to both read and modify its value. The format is

as simple as:

name[index]=value;


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Following the previous examples in which billy had 5 elements and each of those elements was of type int,

the name which we can use to refer to each element is the following:

For example, to store the value 75 in the third element of billy, we could write the following statement:

billy[2]=75;

and, for example, to pass the value of the third element of billy to a variable called a, we could write:

a=billy[2];

Two dimension Array{Two dimension array is represent the element (variable) in the form of rows and columns. If we want to

store the values in matrix form than we can use 2D array. The syntax of two dimension array is show as

below:

Syntax:

Datatype arrayname[rows][cols];

Exp.

Int a[2][3];

In above example array a represent 2 rows and 3 cols. It means total 12 element can be store in array a.

Initialization of 2D array:

According to the simple variable an array variable is also initialization by used assignment operator and

scanf() function

Using assignment operator:

a[0][0]=45;

a[0][1]=43;

a[0][2]=76;

a[1][0]=45;

a[1][1]=43;

a[1][2]=76;

Using scanf() Function operator:

for(int i=0;i


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}

Program for addition of two matrix:#include

void main()

{int a[3][3]={5,6,7,8,6,5,4,3,4};

int b[3][3]={6,8,7,5,3,2,1,2,3};

int c[3][3],p,q;

for(p=0;p


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for(p=0;p


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Initialization of null-terminated character sequences

Because arrays of characters are ordinary arrays they follow all their same rules. For example, if we want

to initialize an array of characters with some predetermined sequence of characters we can do it just like

any other array:

char myword[] = { 'H', 'e', 'l', 'l', 'o', '\0' };

In this case we would have declared an array of 6 elements of type char initialized with the characters that

form the word "Hello" plus a null character '\0' at the end.

But arrays of char elements have an additional method to initialize their values: using string literals.

Double quoted strings (") are literal constants whose type is in fact a null-terminated array of characters.

So string literals enclosed between double quotes always have a null character ('\0') automatically

appended at the end.

we can initialize the array of char elements called myword with a null-terminated sequence of

characters by either one of these two methods:

1. char myword [] = { 'H', 'e', 'l', 'l', 'o', '\0' };

2. char myword [] = "Hello";In both cases the array of characters myword is declared with a size of 6 elements of type char: the 5

characters that compose the word "Hello" plus a final null character ('\0') which specifies the end of the

sequence and that, in the second case, when using double quotes (") it is appended automatically.

String input/output function :

Character Input function

getchar();

exp:

char a;

a=getchar();

getch();

exp:

char a;

a=getch();

getche();

exp:

char a;

a=getche();


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PointerWe have already seen how variables are seen as memory cells that can be accessed using their identifiers.

This way we did not have to care about the physical location of our data within memory, we simply used

its identifier whenever we wanted to refer to our variable.

The memory of your computer can be imagined as a block of memory cells, each one of the minimal sizethat computers manage (one byte). These single-byte memory cells are numbered in a consecutive way.

This way, each cell can be easily located in the memory because it has a unique address and all the

memory cells follow a successive pattern. For example, if we are looking for cell 1776 we know that it is

going to be right between cells 1775 and 1777, exactly one thousand cells after 776 and exactly one

thousand cells before cell 2776.

Reference operator (&)

we declare a variable, the amount of memory needed is assigned for it at a specific location in memory We

generally do not actively decide the exact location of the variable within the panel of cells that we have

imagined the memory to be - Fortunately, that task automatically performed by the operating systemduring runtime. However, in some cases we may be interested in knowing the address where our variable

is being stored during runtime in order to operate with relative positions to it.

The address that locates a variable within memory is what we call a reference to that variable. Thisreference to a variable can be obtained by preceding the identifier of a variable with an ampersand sign

(&), known as reference operator

Consider the following code

Pqr= 25;

abc = pqr;

xyz = &pqr

The values contained in each variable after the execution of this, are shown in the following diagram:

pqr

1775 1776 1777

abc xyz

First, we have assigned the value 25 to pqr (a variable whose address in memory we have assumed to be

1776).

The second statement copied to abc the content of variable pqr (which is 25). This is a standard

assignment operation, as we have done so many times before.

Finally, the third statement copies to xyz not the value contained in pqr but a reference to it (i.e., its

address, which we have assumed to be 1776). The reason is that in this third assignment operation we have

preceded the identifierpqr with the reference operator (&),

The variable that stores the reference to another variable is call apointerVariable. Pointers are a verypowerful feature of the C language., we will see how this type of variable is used and declared.

Declaring variables of pointer types

Like the simple variable pointer variable is declared before use it. The syntax of pointer variabledeceleration is shown as following :

25

25 1776


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The declaration of pointers follows this format:

Datatype * Pointer-variable name;

Exp:

int *p;

where int is the data type of the pointer variable P .This type is not the type of the pointer itself! but the

type of the data the pointer points to. For example:

int * number;

char * character;

float * greatnumber

These are three declarations of pointers variables. Each one is intended to point to a different data type, but

in fact all of them are pointers and all of them will occupy the same amount of space in memory of apointer they are said to have different types: int*, char* and float* respectively, depending on the type they

point to.

.

Function:

Function Contain a block of statements that performs a specific task. in c program It has a name and it is reusable i.e. it

can be executed from as many different parts in a C Program as required. It also optionally returns a value to the calling

program

So function in a C program has some properties discussed as below.

Every function has a unique name. This name is used to call function from main() function. A function can be

called from within another function.

A function is independent and it can perform its task without interfering with other parts of the program.

A function performs a specific task. A task is a different job that Our program must perform as a part of its

overall operation, such as adding two or more integer, sorting an array into numerical order, or calculating a cube

root etc.


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A function returns a value to the calling program. This is optional and depends upon the task our function is

going to accomplish. Suppose we want to just show few lines through function then it is not necessary to return a

value. But if we are calculating area of rectangle and wanted to use result somewhere in program then we have to

send back (return) value to the calling function.

C language is collection of various inbuilt functions. If we have written a program in C then it is evident that you have

used Cs inbuilt functions.Printf, scanf, clrscr getchar() etc. all are Cs inbuilt functions.

Function Declaration:

Function declaration is specified three things

Function return type

Function name

Function list of arguments

Return type function-name(argument list);

In the above example function return type is refer to the type of the value that is returned by the function.

and function-name specifies the name of functions which should be a valid identifier and the list of

arguments is enclosed within a pair of parenthesis. Each argument should be separated by comma.

Function Definition:

Syntax of a Function

A general Syntax of a C function looks like this:

FunctionName (Argument1, Argument2, Argument3)

{

Statement1;

Statement2;

Statement3;

}

An example of function.

int sum (int x, int y)

{

int t;

t = x + y;

return (t); or return t;

}

Advantages of using functions:
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There are many advantages in using functions in a program they are:

1. It makes possible top down modular programming. In this style of programming, the high level logic of the

overall problem is solved first while the details of each lower level functions is addressed later.

2. The length of the source program can be reduced by using functions at appropriate places.

3. A function may be used later by many other programs this means that a c programmer can use function written by

others, instead of starting over from build a New function.

4. A function can be used to keep away from rewriting the same block of codes which we are going use two or more

locations in a program. This is especially useful if the code involved is long or complicated.

Types of functions:

A function may belong to any one of the following categories:

1. Functions with no return values and no arguments.2. Functions with return values and no arguments

3. Functions with no return values and arguments

4. Functions with return values and arguments

Example of a simple function to add two integers.

#include

void add(int x, int y) /*function Declaration and definition

{int t;

t = x+y;

printf("Sum of %d and %d is : %d.\n ",x,y,t);

}

void main()

{

add(10,15); /*function calling

add(55,64);

add(168,325);

}

Program Output

Sum of 10 and 15 is : 25

Sum of 55 and 64 is : 119

Sum of 168 and 325 is :493

Recursion:

Recursion is technique of defining a set or a process in terms of itself. When a function is called

itself that concept is know as recursion.. A recursion function calls itself. Recursion call of function

can either condition ot unconditional. The conditional recursion function termination when certaincondition will be true and An unconditional recursive function causes the infinite sequence of calls.

/* Find the factorial of any number using recursion */


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#include

int fact(int);

void main( )

{

Int a;

printf(Enter Number for find factorial : );scanf(%d,&a);

printf(Output = %d,fact(a));

}

int fact(int b)

{

If(b==0)

{

return(1);

}

else{

return(b*fact(b-1));

}

}

Structure:

Notes C Language

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