#include<stdio.h> /*ERROR*\
int mul(int x, int y);
int main()
{
int a, b, c;
a = 5;
b = 10;
c = mul (a,b);
printf ("multipilcation of %d and %d is %d",a,b,c);
return 0;
}
int p; /* INTER CHANGED LINE *\
int mul(int x, int y)
{
p=x*y;
return p;
}
YOUR MISTAKE IS :
!.FORGOTTEN TO INCLUDE HEADER FILE (i.e, #include<stdio.h>)
2.YOU INTER CHANGE THE DECLARION OF P LINE AND DECLARATION OF FUNCTIONS.