How to create a "X" terminated string in C?

Question

I'm trying to create a counter that counts the amount of characters in a string before "?". I have issues with using strcmp to terminate the while-loop and end up with a segmentation fault. Here's what I have:

void printAmount(const char *s)
{
    int i = 0;
    while ( strcmp(&s[i], "?") != 0 ) {
        i++;
    }
    printf("%i", i);
}

Answer 1

Don't use strcmp for this. Just use the subscript operator on s directly.

Example:

#include <stdio.h>

void printAmount(const char *s) {
    int i = 0;
    while (s[i] != '?' && s[i] != '\0') {
        i++;
    }
    printf("%d", i);
}

int main() {
    printAmount("Hello?world"); // prints 5
}

Or use strchr

#include <string.h>

void printAmount(const char *s) {
    char *f = strchr(s, '?');
    if (f) {
        printf("%td", f - s);
    }
}