Thread: A practical recursive function, finally!

Many years ago, in my very first programming class in college, I was introduced to the concept of recursion. I loved it! I wanted to use it. For a number of years after that I was on the lookout for a practical application of recursion. But I eventually gave up.

Every recursive function that I wrote and every one that I ran across could be done better with a simple loop. Until now.

This function matches a pattern with an arbitrary number of * and ? wildcard characters against a filename (without wildcards) and returns true or false.

I'm sure it could be written more efficiently without recursion, but I can't see a way to keep it simple without recursion. (In this application, speed is less important than simplicity.)

I'm pleased. I hope you are too.

Code:

int Match(const char *pattern, const char *filename)
{
    if (NULL == pattern  ||  NULL == filename)
    {
        return false;
    }

    // Match characters and '?' up to the first '*'

    while (0 != *pattern  &&  0 != *filename  &&  '*' != *pattern  &&
           (toupper(*pattern) == toupper(*filename)  ||  '?' == *pattern))
    {
        pattern++;
        filename++;
    }
    int match = (0 == *pattern  &&  0 == *filename);

    // Use iterative recursion to match everything beyond the first '*'

    if ('*' == *pattern++)
    {
        do {
            match = Match(pattern, filename);
        } while (!match  &&  0 != *filename++);
    }
    return match;
}