Matches a string against a string set, tells you which one it matched

strset.c

#include <stdio.h>
#include <stdlib.h>


/*
 * matches str to one of the strings in set (at most 32),
 * returns the matched string or NULL
 */
char* strset(char** set, char* str) {
    char* mset[32];
    char** msetcur;
    char** setcur;
    char** msetend;
    char* msetstr;
    char c;
    size_t i;

    if (!str || !set || !*set) {
        return NULL;
    }

    msetcur = mset;
    setcur = set;
    while ((*msetcur++ = *setcur++))
        continue;
    msetend = msetcur - 1;

    i = 0;
    do {
        c = str[i];
        for (msetcur = mset; (msetstr = *msetcur); ) {
            if (msetstr[i] == c) {
                ++msetcur;
            } else {
                *msetcur = *--msetend;
                *msetend = NULL;
            }
        }
        if (!*mset) {
            return NULL;
        }
        ++i;
    } while (c);

    return *mset;
}


int main() {
    char* set[] = {"foo", "bar", "baz", NULL};
    printf("%s: %s\n", "foo", strset(set, "foo"));
    printf("%s: %s\n", "bar", strset(set, "bar"));
    printf("%s: %s\n", "baz", strset(set, "baz"));
    printf("%s: %s\n", "ba_", strset(set, "ba_"));
    printf("%s: %s\n", "bazz", strset(set, "bazz"));
    printf("%s: %s\n", "fo", strset(set, "fo"));
    printf("%s: %s\n", "", strset(set, ""));
    return 0;
}