## INDEX

### Why we should use the function?

1. Function reduces the redundancy of code.

Example: 1

Write a c program to find the sum of: 1! /5+ 2! /4+ 3! /3+ 4! /2+ 5! /1 without using function (Except main function). Where! Symbol indicates factorial of any number.

void main(){

int num, sum=0;

int fact1,fact2,fact3,fact4,fact5;

fact1=fact2=fact3=fact4=fact5=1;

num=0;

while(num<=0){

fact1 =fact1+fact1*num;

num++;

}

num=0;

while(num<=1){

fact2 =fact2+fact2*num;

num++;

}

num=0;

while(num<=2){

fact3 =fact3+fact3*num;

num++;

}

num=0;

while(num<=3){

fact4 =fact4+fact4*num;

num++;

}

num=0;

while(num<=4){

fact5 =fact5+fact5*num;

num++;

}

clrscr();

sum=fact1/1+fact2/2+fact3/3+fact4/4+fact5/5;

printf("%d",sum);

getch();

}

Example: 2

Write the same code using function?

void main(){

int sum;

sum=fact(1)/1+fact(2)/2+fact(3)/3+fact(4)/4+fact(5)/5;

clrscr();

printf("%d",sum);

getch();

}

int fact(int x){

int num=0,fact=1;

while(num<=x-1){

fact =fact+fact*num;

num++;

}

return fact;

}

Compare the example one and two and find out the importance of function. You will find out function reduces the repetition of same code.

2. It breaks down a large program in small modules to improve readability, portability as well as makes the program easy to debug.