Functions IN C

FUNCTIONS IN C

Functions

--------------

It avoids the repeated process

A function that calls is referred is function call and a function that is called is referred as called function

Function Definition

------------------------

returntype functionname( arg1,arg2...)

{

statements;

}

Function Declaration or Function prototype

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Syntax

---------

returntype functionname(arg1,arg2...);

There are 4 types of function

1)Function with no argument and no return

2)Function with no argument but return values

3)Function with argument but no return values

4)Function with argument and with return value

Function with no argument and no return

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#include<stdio.h>

#include<conio.h>

void name( );        --->Function prototype

void main()

{

clrscr();

name();                 ---> Function call

getch();

}

void name()          --->Function definition

{

printf("name");

}

}

Function with no argument but return values

----------------------------------------------------------

#include<stdio.h>

#include<conio.h>

float pi();                  ---->Function prototype

void main()

{

int r;

float area;

printf("enter the radius");

scanf("%d",&r);

area=pi() *r*r;          ----> pi() is a function call

printf("area is %f",area);

getch();

}

float pi()

{

return(3.14);            ---->returns value for pi as 3.14

}

Function with argument but no return values
----------------------------------------------------------

#include<stdio.h>

#include<conio.h>

int rev(int);

void main()

{

int n,r;

printf("enter the number");

scanf("%d",&n);

r=rev(n);

getch();

}

int rev(int n)

{

int d,r=0;

while(n>0)

{

d=n%10;

r=r*10+d;

n=n/10;

}

printf("the reversed number is %d",r);

}

Function with argument and with return value

-----------------------------------------------------------

Reversing a number

--------------------------

#include<stdio.h>

#include<conio.h>

int rev(int);

void main()

{

int n,r;

printf("enter the number");

scanf("%d",&n);

r=rev(n);

printf("the original number is %d",n);

printf("the reverse is %d",r);

getch();

}

int rev(int n)

{

int d,r=0;

while(n>0)

{

d=n%10;

r=r*10+d;

n=n/10;

}

return(r);

}

Armstrong number

-------------------------

#include<stdio.h>

#include<conio.h>

int arms(int n)

void main()

{

int n;

printf("enter the number");

scanf("%d",&n);

if(arms(n))

printf("%d is an armstrong number");

else

printf("%d is not an armstrong number");

getch();

}

int arms(int n)

{

int d,s=0,n1;

n1=n;

while(n>0)

{

d=n%10;

s=s+d*d*d*;

n=n/10;

}

if(s==n1)

return 1;

else

return 0;

}

Adam number

--------------------

#include<stdio.h>

#include<conio.h>

int adam(int);

int rev(int)

void main()

{

int n;

printf("anter a number");

scanf("%d",&n);

iif(adam(n))

printf("%d ia an adam number");

else

printf("%d is not an adam number");

getch();

}

int rev(int n)

{

int d,r=0;

while(n>0)

{

d=n%10;

r=r*10+d;

n=n/10;

}

return r;

}

int adam(int n)

{

int t,r;

t=n;

n=n*n;

r=rev(n);

n=sqrt(r);

n=rev(n);

if(n==t)

return 1;

else

return 0;

}

Swap

---------

#include<stdio.h>

#include<conio.h>

void swap(int,int);

void main()

{

int a=10,b=20;

clrscr();

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

swap(a,b);

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

getch();

}

void swap(int x,int y)f=1;

x=y;

y=t;

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

}

Factorial

-----------

#include<stdio.h>

#include<conio.h>

void main()

{

int n,f;

printf("enter the value of n");

scanf("%d",&n);

f=fact(n);

printf("the factorial is %d",f);

getch();

}

int fact(int n)

{

int i,f=1;

for(i=n;i>1;i--)

f=f*i;

return f;

}

Recursive functions

-------------------------

A function that calls itself is called as recursive

Sum of n numbers

------------------------

#include<stdio.h>

#include<conio.h>

int sum(int);

void main()

{

int n,s;

clrscr();

printf("enter n value");

scanf("%d",&n);

s=sum(n);

printf("the sum is %d",s);

getch();

}

int sum(int n)

{

int s=0;

if(n>0)

s=n+sum(n-1);

return s;

}

Factorial

------------

#include<stdio.h>

#include<conio.h>

void main()

{

int n,f;

printf("enter the value of n");

scanf("%d",&n);

f=fact(n);

printf("the factorial is %d",f);

getch();

}

int fact(int n)

{

int i,f=1;

if(n>1)

f=n*fact(n-1);

return f;

}