Sunday, July 8, 2007

Write a C program which does wildcard pattern matching algorithm.

Here is an example C program...


#include < stdio.h >
#define TRUE 1
#define FALSE 0

int wildcard(char *string, char *pattern);

int main()
{
char *string = "hereheroherr";
char *pattern = "*hero*";

if(wildcard(string, pattern)==TRUE)
{
printf("\nMatch Found!\n");
}
else
{
printf("\nMatch not found!\n");
}
return(0);
}

int wildcard(char *string, char *pattern)
{
while(*string)
{
switch(*pattern)
{
case '*': do {++pattern;}while(*pattern == '*');
if(!*pattern) return(TRUE);
while(*string){if(wildcard(pattern,string++)==TRUE)return(TRUE);}
return(FALSE);
default : if(*string!=*pattern)return(FALSE); break;
}
++pattern;
++string;
}

while (*pattern == '*') ++pattern;
return !*pattern;
}

5 comments:

vikash said...

Here is the working code:-

#include
#define TRUE 1
#define FALSE 0

int wildcard(char *string, char *pattern);

int main()
{
char *string = "iereherojerr";
char *pattern = "*hero*";

if(wildcard(string, pattern)==TRUE)
{
printf("\nMatch Found!\n");
}
else
{
printf("\nMatch not found!\n");
}
return(0);
}


int wildcard(char *string, char *pattern)
{
while(*string)
{
switch(*pattern)
{
case '*': do {
++pattern;
} while(*pattern == '*');

if(!*pattern)
{
return(TRUE);
}

while(*string != '\0')
{
if(*pattern != *string) string++;
else break;

}
/*while(*pattern != *string)
{
if(!*pattern) return FALSE;
string++;
}*/

// while(*string)
{
if(wildcard(string++,pattern++)==TRUE)
return(TRUE);
}

return(FALSE);
default :
while(*pattern != '\0')
{
if(*pattern == '*')
{
if(wildcard(string, pattern) == TRUE)
return (TRUE);

}

if(*string !=*pattern)
{
return(FALSE);
}
pattern++;
string++;
}
return TRUE;
break;
}
++pattern;
++string;
}

while (*pattern == '*') ++pattern;
return !*pattern;
}

AaronMiller said...

http://codepad.org/vdkJgqw6

Use const to indicate your function will not write to the string.

Recursion is unnecessary.

Anonymous said...

wildcard("ab*d", "abcdd") returns false, but I would expect true. The same applies to the code found at the codepad link.

See wikipedia's definition of wildcard: https://en.wikipedia.org/wiki/Wildcard_character

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