Question

I am trying to write a small program where I basically count the string length in a function but for some reason it is not outputting anything to the command line.

#include <stdio.h>

int search (char* string, char* substring){
    int length = 0;
    while(substring){
        substring++;
        length++;
    }
    return length;

}


int main(int argc, const char * argv[])
{
    char string1[] = "hello world";
    char* string = string1;
    char substring1[] = "world";
    char* substring = substring1;

    int a = search(string,substring);

    printf("%d", a);
    return 0;
}

Answer 1

You need to dereference it or you’ll keep looping since there’s no obvious way for substring to become 0.

while (*substring)
       ^

That’s because you’re not looking for the NULL pointer but rather for the NUL (\0) character.