#include <string.h> // for access to size_t and the "official" strlen
#include <stdio.h> // for access to printf

size_t strlen1(const char *s) {
    size_t ans = 0;
    while(s[ans]) ans+=1;
    return ans;
}

size_t strlen2(const char *s) {
    size_t ans = 0;
    const char *p = s;
loop:
    if (!*p) goto end;
    ans += 1;
    p += 1;
    goto loop;
end:
    return ans;
}

size_t strlen3(const char *s) {
    size_t ans = -1;
loop:
    ans += 1;
    if (s[ans]) goto loop;
    return ans;
}


int main(int argc, char *argv[]) {
    const char *s = "This is a ☺ test";
    printf("strlen(\"%s\") = %zd\n", s, strlen(s));
    printf("strlen1(\"%s\") = %zd\n", s, strlen1(s));
    printf("strlen2(\"%s\") = %zd\n", s, strlen2(s));
    printf("strlen3(\"%s\") = %zd\n", s, strlen3(s));
    return 0;
}