C++ Password increment by alphabet

char* convertToWord(size_t value, const char* alphabet, size_t alphabetLen) {
    if (value < alphabetLen) {
        char* word = (char*)calloc(2, 1);
        word[0] = alphabet[value];
        return word;
    }

    size_t wordLen = 0;
    for (size_t v = value; v > 0; wordLen++) {
        v /= alphabetLen;
    }

    char* word = (char*)calloc(wordLen+1, 1);

    size_t i = 0;
    for (; value >= alphabetLen; i++) {
        word[i] = alphabet[value % alphabetLen];
        value /= alphabetLen;
    }
    word[i] = alphabet[(value % (alphabetLen + 1)) - 1];
    return word;
}