Created
February 27, 2012 23:45
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Brian Kernighan's Solution
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/* match: search for regexp anywhere in text */ | |
int match(char *regexp, char *text) | |
{ | |
if (regexp[0] == '^') | |
return matchhere(regexp+1, text); | |
do { /* must look even if string is empty */ | |
if (matchhere(regexp, text)) | |
return 1; | |
} while (*text++ != '\0'); | |
return 0; | |
} | |
/* matchhere: search for regexp at beginning of text */ | |
int matchhere(char *regexp, char *text) | |
{ | |
if (regexp[0] == '\0') | |
return 1; | |
if (regexp[1] == '*') | |
return matchstar(regexp[0], regexp+2, text); | |
if (regexp[0] == '$' && regexp[1] == '\0') | |
return *text == '\0'; | |
if (*text!='\0' && (regexp[0]=='.' || regexp[0]==*text)) | |
return matchhere(regexp+1, text+1); | |
return 0; | |
} | |
/* matchstar: search for c* regexp at beginning of text */ | |
int matchstar(int c, char *regexp, char *text) | |
{ | |
do { /* a * matches zero or more instances */ | |
if (matchhere(regexp, text)) | |
return 1; | |
} while (*text != '\0' && (*text++ == c || c == '.')); | |
return 0; | |
} |
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