#define _GNU_SOURCE
#include <ctype.h>
#include <string.h>

int strverscmp(const char* l0, const char* r0) {
    const unsigned char* l = (const void*)l0;
    const unsigned char* r = (const void*)r0;
    size_t i, dp, j;
    int z = 1;

    /* Find maximal matching prefix and track its maximal digit
     * suffix and whether those digits are all zeros. */
    for (dp = i = 0; l[i] == r[i]; i++) {
        int c = l[i];
        if (!c)
            return 0;
        if (!isdigit(c))
            dp = i + 1, z = 1;
        else if (c != '0')
            z = 0;
    }

    if (l[dp] != '0' && r[dp] != '0') {
        /* If we're not looking at a digit sequence that began
         * with a zero, longest digit string is greater. */
        for (j = i; isdigit(l[j]); j++)
            if (!isdigit(r[j]))
                return 1;
        if (isdigit(r[j]))
            return -1;
    } else if (z && dp < i && (isdigit(l[i]) || isdigit(r[i]))) {
        /* Otherwise, if common prefix of digit sequence is
         * all zeros, digits order less than non-digits. */
        return (unsigned char)(l[i] - '0') - (unsigned char)(r[i] - '0');
    }

    return l[i] - r[i];
}