`

#include<stdio.h>



 main()
{
int b,c;
printf("enter c :");
scanf("%d",&c);
printf("enter b :");
scanf("%d",&b);

printf("%d",          gem());
getch();
return 0;      
}

int  gem(int b,int c)
{
    int a;
    a=b+c;
    return a;
}

`

You've defined gem to take 2 arguments, but you're calling it without any arguments.

You should also forward-declare gem or define it before the main function.

You don't have a prototype for gem(), you're not passing the required arguments, getch() requires conio.h to be included, and relying in implicit int for main()'s return type is poor practice give that this feature was removed in C99.