# function program in c

In this article function program in c we give the simple, conditional, looping based program are covered using user defined function and show the proper output in details.

#### Function program in C:

// Function with arguments but return a value

// Write a C Program to calculate addition of two number using function.

#include<stdio.h>

#include<conio.h>

int total(int a, int b);        // function declaration

void main()

{

int a,b,sum=0;

clrscr();

printf(“\n Enter the two numbers: “);

scanf(“%d%d”,&a,&b);

sum=total(a,b);      // function call

printf(“\n\n Addition of Two numbers: %d”,sum);

getch();

}

int total(int a, int b)       // function defination

{

return(a+b);

}

Output:

Enter the two numbers: 8

9

// To find area of rectangle using user defined function

#include<stdio.h>

#include<conio.h>

int area_rect(int ,int );      // function declaration

void main()

{

int l,b,area=0;

clrscr();

printf(“\n\n Enter the length and breadth: “);

scanf(“%d%d”,&l,&b);

area=area_rect(l,b);        // function call

printf(“\n\n Area of Rectangle: %d”,area);

getch();

}

int area_rect(int l,int b)         // function defination

{

return(l*b);

}

Output:

Enter the length and breadth: 6

4

Area of Rectangle: 24

/* Write a C Program to interchange two values

by using user defined function */

#include<stdio.h>

#include<conio.h>

void swap(int,int);      // function declaration

void main()

{

int a,b;

clrscr();

printf(“\n Enter the two numbers: “);

scanf(“%d%d”,&a,&b);

swap(a,b);     // function call

getch();

}

void swap(int a, int b)      // function defination

{

int temp;

printf(“\n\n Before Swap \n”);

printf(“\t%d\t%d”,a,b);

temp=a;

a=b;

b=temp;

printf(“\n\n After Swap \n”);

printf(“\t%d\t%d”,a,b);

}

Output:

Enter the two numbers: 50

100

Before Swap

50                    100

After Swap

100                 50

#### Function program in C:

/* Write a C Program to find given number is odd/even

by using user defined function */

#include<stdio.h>

#include<conio.h>

void oddeven(int);    // function declaration

void main()

{

int n;

clrscr();

printf(“\n Enter the number: “);

scanf(“%d”,&n);

oddeven(n);     // function call

getch();

}

void oddeven(int n)             // function defination

{

if(n%2==0)

printf(“\n %d is even number.”, n);

else

printf(“\n %d is odd number.”, n);

}

Output:

Enter the number: 100

100 is even number.

/* Write a C Program to find smallest number among three

Different numbers using function */

#include<stdio.h>

#include<conio.h>

void smallest3(int,int,int);     // function declaration

void main()

{

int x,y,z;

clrscr();

printf(“\n Enter the three numbers: “);

scanf(“%d%d%d”,&x,&y,&z);

smallest3(x,y,z);           // function call

getch();

}

void smallest3(int x, int y, int z)         // function defination

{

if(x<y && x<z)

{

printf(“\n First number is Smallest number: %d”, x);

}

else

if(y<z)

{

printf(“\n Second number is Smallest number: %d”, y);

}

else

{

printf(“\n Thired number is Smallest number: %d”, z);

}

}

Output:

Enter the three numbers: 10

20

30

First number is smallest number: 10

/* Write a C Program to show sum of digits

using user defined function  */

#include<stdio.h>

#include<conio.h>

int sumdig(int n);              // function declaraion

void main()

{

int n,sumd=0;

clrscr();

printf(“\n Enter the number: “);

scanf(“%d”,&n);

sumd=sumdig(n);       // function call

printf(“\n\n Sum of digit=%d”, sumd);

getch();

}

int sumdig(int n)               // function defination

{

int dig=0,sum=0;

while(n>0)

{

dig=n%10;

sum=sum+dig;

n=n/10;

}

return sum;

}

#### Output:

Enter the number: 123

Sum of digit = 6

#### Function program in C:

/* write a C Program to show reverse number
by using user defined function */
#include<stdio.h>
#include<conio.h>
int reverse(int); // function declaration
void main()
{
int n,r=0;
clrscr();
printf(“\n Enter the number: “);
scanf(“%d”,&n);
r=reverse(n); // function call
printf(“\n\n Reverse number: %d”,r);
getch();
}
int reverse(int n) // function definition
{
int rev=0, dig=0;
while(n>0) // 123           12         1 0
{
dig=n%10; // 3         2           1
rev=(rev*10)+dig; // 3            32             321
n=n/10; // 12            1           0
}
return rev;
}

Output:

Enter the number: 123

Reverse number: 321

/* write a C Program to show Palindrome number
by using user defined function
ex. 121 = 121 , 535 = 535 etc.
*/
#include<stdio.h>
#include<conio.h>
int reverse(int); // function declaration
void main()
{
int n,r=0,t=0;
clrscr();
printf(“\n Enter the number: “);
scanf(“%d”,&n);
t=n;
r=reverse(n); // function call
if(r==t)
printf(“\n\n %d is a Palindrome number.”, r);
else
printf(“\n\n %d is not a Palindrome number.”, t);
getch();
}
int reverse(int n) // function definition
{
int rev=0, dig=0;
while(n>0) // 123 12 1 0
{
dig=n%10; // 3 2 1
rev=(rev*10)+dig; // 3 32 321
n=n/10; // 12 1 0
}
return rev;
}

Output:

Enter the number: 121

121 is a Palindrome number.

/* write a C Program to show  armstrong number
by using user defined function */
#include<stdio.h>
#include<conio.h>
int armstrong(int);      // function declaration
void main()
{
int n,r=0,t=0;
clrscr();
printf(“\n Enter the number: “);
scanf(“%d”,&n);
t=n;
r=armstrong(n);      // function call
if(t==r)
printf(“\n\n %d is Armstrong number.”,r);
else
printf(“\n\n %d is Not Armstrong number.”,t);
getch();
}
int armstrong(int n)            // function defination
{
int sum=0, dig=0;
while(n>0)   // 123            12    1   0
{
dig=n%10;            // 3    2   1
sum=sum+(dig*dig*dig);    // 3    32  321
n=n/10;              // 12   1   0
}
return sum;
}
Output:
Enter the number: 153
153 is Armstrong number.

#### Function program in C:

/* write a C Program to show prime number
by using user defined function */
#include<stdio.h>
#include<conio.h>
int prime(int); // function declaration
void main()
{
int n;
clrscr();
printf(“\n Enter the number: “);
scanf(“%d”,&n);
prime(n); // function call
getch();
}
int prime(int n) // function defination
{
int d=2;
while(n>d) // 5>2 5>3 5>4 5>5
{
if(n%d==0) // 1 2 1
{
printf(“\n\n %d is not prime number.”,n);
break;
}
else
{
d++; // 3 4 5
}
}
if(n==d)
printf(“\n\n %d is a Prime number.”,n);
return 0;
}
Output:
Enter the number: 5
5 is a Prime number.