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Diffstat (limited to 'reference/C/CONTRIB/SNIP/patmat.c')
| -rwxr-xr-x | reference/C/CONTRIB/SNIP/patmat.c | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/reference/C/CONTRIB/SNIP/patmat.c b/reference/C/CONTRIB/SNIP/patmat.c new file mode 100755 index 0000000..da20131 --- /dev/null +++ b/reference/C/CONTRIB/SNIP/patmat.c @@ -0,0 +1,75 @@ +#include <stddef.h>
+#include <string.h>
+
+/***********************************************************************
+** **
+** Function : patmat **
+** **
+** Purpose : Pattern Matching **
+** **
+** Usage : Pass two string pointers as parameters.The first **
+** being a raw string & the second a pattern the raw **
+** string is to be matched against.If the raw string **
+** matches the pattern,then the function returns a **
+** 1,else it returns a 0. **
+** **
+** e.g patmat("abcdefghi","*ghi") returns a 1. **
+** patmat("abcdefghi","??c??f*") returns a 1. **
+** patmat("abcdefghi","*dh*") returns a 0. **
+** patmat("abcdefghi","*def") returns a 0. **
+** **
+** The asterisk is a wild card to allow any charac- **
+** ters from its first appearance to the next spec- **
+** ific character.The character ? is a wild card **
+** for only one character in the position it appears.**
+** Combinations such as "*?" or "?*" or "**" are **
+** illegal for obvious reasons & the functions may **
+** goof,though I think it will still work. **
+** **
+** Author : Sreenath Chary Nov 29 1988 **
+** **
+** Logic : The only simple way I could devise is to use **
+** recursion.Each character in the pattern is **
+** taken & compared with the character in the raw **
+** string.If it matches then the remaining amount **
+** of the string & the remaining amount of the **
+** pattern are passed as parameters to patmat again **
+** until the end of the pattern.If at any stage **
+** the pattern does not match,then we go back one **
+** level & at this level if the previous character **
+** was a asterisk in the pattern,we hunt again from **
+** where we left off,otherwise we return back one **
+** more level with a not found & the process goes **
+** on till the first level call. **
+** **
+** Only one character at a time is considered,except **
+** when the character is an asterisk.You'll get the **
+** logic as the program unfolds. **
+** **
+***********************************************************************/
+
+patmat(char *raw,char *pat)
+{ int i, slraw;
+
+ if ((*pat == '\0') && (*raw == '\0')) /* if it is end of both */
+ return( 1 ) ; /* strings,then match */
+ if (*pat == '\0') /* if it is end of only */
+ return( 0 ) ; /* pat tehn mismatch */
+ if (*pat == '*') /* if pattern is a '*' */
+ { if (*(pat+1) == '\0') /* if it is end of pat */
+ return( 1 ) ; /* then match */
+ for(i=0,slraw=strlen(raw);i<=slraw;i++)/* else hunt for match*/
+ if ((*(raw+i) == *(pat+1)) || /* or wild card */
+ (*(pat+1) == '?'))
+ if (patmat(raw+i+1,pat+2) == 1) /* if found,match */
+ return( 1 ) ; /* rest of pat */
+ }
+ else
+ { if (*raw == '\0') /* if end of raw then */
+ return( 0 ) ; /* mismatch */
+ if ((*pat == '?') || (*pat == *raw)) /* if chars match then */
+ if (patmat(raw+1,pat+1) == 1) /* try & match rest of it*/
+ return( 1 ) ;
+ }
+ return( 0 ) ; /* no match found */
+}
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