#include <stdio.h>
#include <assert.h>

int main()
{
    char x = 7;

    /*  Some big code in between and let's say x
       is accidentally changed to 9  */
    x = 20;

    // Programmer assumes x to be 7 in rest of the code
    #warning "this is warning message"
    #error "there is error message"
    assert(x==7);

    /* Rest of the code */

    return 0;
}