In You Program You can Have Program like this

pro 1
void main()
{
/* */

}

pro 2

int main()
{

/* */

return 0;
}

in pro1 its showing you void main it's mean's RETURN NOTHING just a main Function with your code!! but in pro2 its haveing int main() function it's mean's that function return a value!! so if you put in void main function to return a value u will get an Error so best way is you have to use void main function in your program!!

example

#include <stdio.h>
#include <conio.h>


int call(int x,int y);

void main()
{
int num1,num2,ans;

clrscr();
printf("Enter the First number : ");
scanf("%d",&num1);
printf("\nEnter the Secound Number : ");
scanf("%d",&num2);

/*call the cal function using ans */

ans=call(num1,num2);

printf("The Add of num1 and num2 is %d",ans);

getch();
}

int call(int x,int y)
{
int z;

z=(x+y);

return (z); /* cal function go back to main function*/

}