Re: [MLUG] String manipulation in C

[Jack Smith <EMAIL:PROTECTED>]

I think I have it figured out. I did so by calling my match() below to tell me if there is a match (action = "" If there was a match, I got the starting and ending locations from match() with action = 1 and 2. I set up a cumulative distance counter of pmatch[].rm_eo values returned and then advanced the string to be searched by that many characters. I put that in a while loop to keep advancing the string and looking for matches until there were no more:

/* Sending the match function a string and pattern, getting a status result */
		matchStatus = match(sequence, pattern, 0);

		/* Outputting data */
		printf("%-15d%-15s%-80s", num, names, pattern);

		/* Actions taken if there is a match
		/* Getting the starting and ending locations of a match (if there is one) */
		while(matchStatus == 1) {
			/* Advancing string past the end location of the previous match.
			    Note that this will just copy the string for the first match. */
			strcpy(stringrem, sequence+endLocTotal);

			/* Getting the relative starting and ending locations of the matches */
			startLoc = match(stringrem, pattern, 1);
			endLoc = match(stringrem, pattern, 2);
			
			/* Getting the cumulative distance of the matches from the beginning and end of the sequence */
			startLocTotal = startLocTotal + startLoc;
			endLocTotal = endLocTotal + endLoc;
			
			/* Printing the values of the starting and ending locations if there was a new match */
			if(startLoc > 0) {
				printf("%-7d%-7d", startLocTotal, endLocTotal);
			}

			/* pass sequence after the first match to match() to see if there is another match */
			matchStatus = match(stringrem, pattern, 0);

			/* Flushing values of StartLoc and endLoc */
			startLoc = 0;
			endLoc = 0;
		}

Here's my match function: 

int match(const char *string, char *pattern, int action) {

	/* Declaring function variables */
	int status;
	int i = 1;
	regex_t re;
	regmatch_t pmatch[10];

	/* Compile the regular _expression_ and exit if there is an error with it */
	if(regcomp(&re, pattern,0) != 0) {
		return 0;
	}

	/* Perform the regular _expression_ matching function */
	status = regexec(&re, string, 10, pmatch, 0);

	/* Exit and retun 0 if no match is found */
	if(status != 0) {
		return 0; 	
	}

	/* Returning different results depending on what's being asked of the function */
	/* action = 0 tells the function to return if there is a match or not */
	if(action == 0) {
		if(status == 0) {
			return 1;
		}
		if(status !=0 ) {
			return 0;
		}
	}

	/* action = 1 tells the function to retun the location where the match starts */
	if(action == 1 && status == 0) {
		return pmatch[0].rm_so;
	}

	/* action = 2 tells the function to return the location where the match ends */
	if(action == 2 && status == 0) {
		return pmatch[0].rm_eo;
	}
		
	/* Freeing the memory for pointer to the string */
	regfree(&re);
}

It appears to do just the job that I want and is much faster than MATLAB. Thank you all for your help. 

Jack


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