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Posted 22 Jul 2007

String Wildcard Matching (* and ?)

, 22 Jul 2007
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A simple function to perform wildcard ( * ? ) string matching


I had a problem where I wanted to match a string against a pattern based on wild characters (* and ?). The function presented in this article is a simple one that does this matching. Here are some sample patterns:

  • sam*
  • sam*e
  • samp?e
  • s*p?e
  • etc.

Using the Code

The usage of the function is very simple. Just call the function with two arguments. The first one is the string to be compared with the pattern specified in the second argument. The function does not perform any error checking.


bool pattern_match(const char *str, const char *pattern) {
    enum State {
        Exact,      	// exact match
        Any,        	// ?
        AnyRepeat    	// *

    const char *s = str;
    const char *p = pattern;
    const char *q = 0;
    int state = 0;

    bool match = true;
    while (match && *p) {
        if (*p == '*') {
            state = AnyRepeat;
            q = p+1;
        } else if (*p == '?') state = Any;
        else state = Exact;

        if (*s == 0) break;

        switch (state) {
            case Exact:
                match = *s == *p;

            case Any:
                match = true;

            case AnyRepeat:
                match = true;

                if (*s == *q) p++;

    if (state == AnyRepeat) return (*s == *q);
    else if (state == Any) return (*s == *p);
    else return match && (*s == *p);


  • 22nd July, 2007: Initial post


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

M Shahid Shafiq
Pakistan Pakistan
No Biography provided

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Comments and Discussions

AnswerString wildcard matching (* and ?) Pin
tmowhrekf12-Mar-13 17:59
membertmowhrekf12-Mar-13 17:59 
I was looking for something like this but didn't think much of this code.

After spending some time considering how to implement wildcard matching properly I came up with the following:
// wildcard matching algorithm
// written 2013 by Mathias Karlsson <>
// use freely.
bool wildcard(const char *str, const char *pattern);
bool wildcard(const char *s, const char *p)
	// ? matches one character
	// * matches zero or more characters
	while (*s) {
		if (!*p) return false;
		if (*p == '*') {
			while (*p == '*') p++;
			if (!*p) return true;
			while (*s) if (wildcard(s++, p)) return true;
			return false;
		if (*s != *p && *p != '?') return false;
	while (*p == '*') p++;
	return (!*p);

If you have examples where it would fail then please reply to this or send me a message.

Of course, if there are security concerns you should limit the string lengths and the call stack.

Hopefully this code will help someone.

modified 31-Mar-13 13:59pm.

GeneralRe: String wildcard matching (* and ?) Pin
azorius24-Mar-13 1:10
memberazorius24-Mar-13 1:10 
GeneralRe: String wildcard matching (* and ?) Pin
tmowhrekf24-Mar-13 2:32
membertmowhrekf24-Mar-13 2:32 

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