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Wildcard string compare (globbing)

Jack Handy

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4.90/5 (82 votes)

15 Feb 2005

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Matches a string against a wildcard string such as "*.*" or "bl?h.*" etc. This is good for file globbing or to match hostmasks.

Usage:

This is a fast, lightweight, and simple pattern matching function.

if (wildcmp("bl?h.*", "blah.jpg")) {
  //we have a match!
} else {
  //no match =(
}

Function:

int wildcmp(const char *wild, const char *string) {
  // Written by Jack Handy - <A href="mailto:jakkhandy@hotmail.com">jakkhandy@hotmail.com</A>
  const char *cp = NULL, *mp = NULL;

  while ((*string) && (*wild != '*')) {
    if ((*wild != *string) && (*wild != '?')) {
      return 0;
    }
    wild++;
    string++;
  }

  while (*string) {
    if (*wild == '*') {
      if (!*++wild) {
        return 1;
      }
      mp = wild;
      cp = string+1;
    } else if ((*wild == *string) || (*wild == '?')) {
      wild++;
      string++;
    } else {
      wild = mp;
      string = cp++;
    }
  }

  while (*wild == '*') {
    wild++;
  }
  return !*wild;
}

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

Written By

Jack Handy

Web Developer

United States

This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

Comments and Discussions

Re: Case Insensitive wildcmp

Neville Franks16-Mar-04 9:52

16-Mar-04 9:52

Simply wrap the code that compares charaters in toupper() calls.

eg.

if ((toupper(*wild) != toupper(*string)) && (*wild != '?')) {

Neville Franks, Author of ED for Windows www.getsoft.com and coming soon: Surfulater www.surfulater.com

Re: Case Insensitive wildcmp

23-Mar-04 9:33

23-Mar-04 9:33

toupper doesnt support char characters. You could optimize this code.
This code compares also multilingual characters

<br />
#include <stdio.h><br />
                        <br />
#define BIT5 0x20<br />
                        <br />
char buf[] = "this is ®Ñê test";<br />
char *pbuf;<br />
         <br />
int lower(int ch);<br />
        <br />
                <br />
int lower(int ch)<br />
{<br />
if ((ch==64)||(ch==91)||(ch==92)||(ch==93))<br />
return ch &= ~(ch & BIT5);<br />
    return ch |= BIT5;<br />
}<br />
    <br />
int wildcmp(char *wild, char *string) {<br />
        char *cp, *mp;<br />
        <br />
        while ((*string) && (*wild != '*')) {<br />
                if ((*wild != *string) && (*wild != '?')) {<br />
                        return 0;<br />
                }<br />
                wild++;<br />
                string++;<br />
        }<br />
         <br />
        while (*string) {<br />
                if (*wild == '*') {<br />
                        if (!*++wild) {<br />
                                return 1;<br />
                        }<br />
                        mp = wild;<br />
                        cp = string+1;<br />
                } else if ((*wild == *string) || (*wild == '?')) {<br />
                        wild++;<br />
                        string++;<br />
              } else {<br />
                        wild = mp;<br />
                        string = cp++;<br />
                }<br />
        }<br />
<br />
        while (*wild == '*') {<br />
                wild++;<br />
        }<br />
        return !*wild;<br />
}<br />
<br />
    <br />
int main() {<br />
    <br />
for (pbuf = &buf[0]; *pbuf; ++pbuf)<br />
*pbuf= lower (*pbuf); <br />
        <br />
if (wildcmp("*®ñê*", buf)){<br />
        printf ("match : %s \n", buf);<br />
   } else {<br />
        printf ("not match: %s \n",buf);<br />
 }<br />
}<br />
         <br />
       <br />

Re: Case Insensitive wildcmp

David Crow23-Feb-05 2:24

23-Feb-05 2:24

Techiex wrote:
toupper doesnt support char characters

Since when?

ASSERT('A' == toupper('a'));

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

Re: Case Insensitive wildcmp

Vic Mackey23-Feb-05 8:00

23-Feb-05 8:00

Be careful when using toupper(), some of the CRT variations of this function _only_ work when the input is known to be lowercase. For example, the return value is invalid for _toupper('A') and some implementations of toupper('A') as well...check the documentation.

Re: Case Insensitive wildcmp

David Crow23-Feb-05 8:22

23-Feb-05 8:22

Vic Mackey wrote:
Be careful when using toupper(), some of the CRT variations of this function _only_ work when the input is known to be lowercase.

Which is why I specified toupper() instead of _toupper(). The latter is nothing but a #define directive that does no checking.

In any case, I was simply responding to Techiex's statement that "toupper doesnt support char characters."

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

Re: Case Insensitive wildcmp

f_randy12-Jun-06 18:13

12-Jun-06 18:13

Doesnt seems to work for me.

Excellent code!

Hans Dietrich16-Jul-03 19:40

16-Jul-03 19:40

Very nice, compact, works great and is very fast. Thanks, Jack!

Best wishes,
Hans

checking for null

Jack Handy13-Mar-03 20:38

13-Mar-03 20:38

I've seen a few people in these boards complain that I didn't check for null pointers in this function. This is a C function and the last time I checked, passing NULL to strcmp or any other C string function will segfault. I'm not saying this is great, and if you wanted to add a check for null, that would be fine. I just don't think that this is a 'bug' (if you can even call it that) worth flaming an otherwise great function.

-Jack

There are 10 types of people in this world, those that understand binary and those who don't.

Re: checking for null

Anonymous15-Mar-03 20:10

15-Mar-03 20:10

I agree. This is not what I meant.

Efrat

Re: checking for null

Jack Handy18-Mar-03 13:25

18-Mar-03 13:25

Yeah, I wasn't talking to you, you were respectful. I was talking to the people below in the 'too complicated' thread. Namely 'The C++ Guru'.

-Jack

There are 10 types of people in this world, those that understand binary and those who don't.

great code, but ...

Anonymous12-Mar-03 3:17

12-Mar-03 3:17

great code, but if I'm not mistaken
cp can point beyon string array bounds.
try: wild="*a", string="xyzab"

correction:
string = cp++;
should be changed to:
string = cp;
if(*cp) cp++;

Re: great code, but ...

Jack Handy13-Mar-03 20:34

13-Mar-03 20:34

I can not reproduce this bug.

wildcmp("*a", "xyzab") returns 0 as it should.

Can you elaborate on what you are doing to cause it to function incorrectly?

Thanks,

Jack

Re: great code, but ...

Anonymous15-Mar-03 20:08

15-Mar-03 20:08

You're right, it is not a bug in functionality,
but when I debugged it I saw that
for the above input, the line:
string = cp++;
causes cp to point one place beyond the string array bounds.
(When string points to the last char 'b', cp points to \0.
On the next iteration, string will be advanced to point to \0,
and cp will be advanced to point to one place after the \0).
Although it is not critical,I thought it is worth fixing.

regards,
Efrat

Re: great code, but ...

Jack Handy18-Mar-03 13:25

18-Mar-03 13:25

Thanks, I'll have to look into this once I get some free time.

-Jack

There are 10 types of people in this world, those that understand binary and those who don't.

Re: great code, but ...

Anonymous19-Mar-03 23:13

19-Mar-03 23:13

Actually, it was brought to my attention that it is probably
legal to do that in C, since the pointer is not used afterwards.
So, maybe it's just a matter of coding practice.

Chris Richardson16-Jan-03 10:58

Chris Richardson

16-Jan-03 10:58

I saw this one a long time ago, and finally have a use for it. Thank you very much.

Chris Richardson

Programmers find all sorts of ingenious ways to screw ourselves over. - Tim Smith

Jack Handy20-Jan-03 11:56

20-Jan-03 11:56

No problem. I hope it serves you well.

-Jack

There are 10 types of people in this world, those that understand binary and those who don't.

Anonymous6-Dec-02 11:09

6-Dec-02 11:09

I converted this into C# and bingo...

I tried to break it but couldn't Smile | :)

Smile | :)

hector santos1-Mar-03 1:53

1-Mar-03 1:53

You didn't try hard enough:

wildcmp(NULL,whatever)

will break it. Big Grin | :-D

Big Grin | :-D

Hector Santos, CTO
Santronics Software, Inc.
http:/www.santronics.com

Kent C. Dorner2-Mar-03 5:32

Kent C. Dorner

2-Mar-03 5:32

The C# code would NOT break, instead the framework would throw an exception in this case. With appropriate exception handling routines, pointer checking in C# is useless overhead.

Cheers anyway,

K. C. Dorner
IBM Billing Solution

gebrudergrimm28-Dec-03 10:18

28-Dec-03 10:18

Exception handling in the dotnet framework is slow like hell

we will see

BrcKcc15-Jun-04 8:18

15-Jun-04 8:18

Where can I get the C# version?
- Bruce

BRCKCC

Yes man - you a really cool developer

Stanislav Panasik23-Oct-02 19:06

Stanislav Panasik

23-Oct-02 19:06

Hi !

Wery useful function, Smile | :)

Smile | :)

save at least a one sigarette lifetime Smile | :)

Smile | :)

Seriously - great code.

Stanislav.

Re: Yes man - you a really cool developer

Anonymous28-Mar-04 13:43

28-Mar-04 13:43

Yeah...good stuff. How long did it take you?

blahblah18-Apr-02 10:45

18-Apr-02 10:45

Could anyone explain how this code works for me? I am having trouble trying to figure out what is going on in a couple places. I would think a short explination would help out some other people like me who don't know C. Thanks in advance!

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