Thread: memory allocation problem

hi,

there is a memory allocation problem in this method..because although it compiles and runs ok...it stuffs up one of my other variables...

can someone please help

thanks alot

Code:

char* setSearchTag(char *search) {

	char *newSearchTag;
	char *startTag = "<";
	char *endTag = ">";
	int newSearchTagLength = strlen(search) + strlen(startTag) + strlen(endTag);	
	

	if ((newSearchTag = ( char * )malloc(sizeof(char) * (newSearchTagLength)+1)) == NULL){
		fprintf(stderr, "Unable to allocate %d bytes of memory for current search\n", newSearchTagLength+1);
		exit(1);
	}		

	strcpy(newSearchTag, startTag);
	strcat(newSearchTag,search);
	strcat(newSearchTag,endTag);

	return newSearchTag;
				
}

this is a c programming board... go post this in c++ im sure someone will be able to help you

this is C....???? compiled using gcc!...anyone know how to fix

maybe u needed more detail to help me...

here is where i called it...and the variable that was stuffing up is file (passed into searchForTags()...

Code:

void searchForTags(char *file) {
	
	char *currentSearch;
	int *startOfData;
	int *endOfData;
	char *titles;	

	currentSearch = setSearchTag("title");
	startOfData = search(file, currentSearch, "start");
	

	currentSearch = setSearchTag("/title");	
	endOfData = search(file, currentSearch, "end");
	
}

char* setSearchTag(char *search) {

	char *newSearchTag;
	char *startTag = "<";
	char *endTag = ">";
	int newSearchTagLength = strlen(search) + strlen(startTag) + strlen(endTag);	
	

	if ((newSearchTag = ( char * )malloc(sizeof(char) * (newSearchTagLength)+1)) == NULL){
		fprintf(stderr, "Unable to allocate %d bytes of memory for current search\n", newSearchTagLength+1);
		exit(1);
	}		

	strcpy(newSearchTag, startTag);
	strcat(newSearchTag,search);
	strcat(newSearchTag,endTag);

	return newSearchTag;
				
}

i still couldnt find the problem...i steped through setSearchTag()...it does exactly what i want...but if...i print the variable file before and after the method call...it changes....which is really odd...ill post my code again with the search function...thanks again for anyhelp

Code:

void searchForTags(char *file) {
	
	char *currentSearch;
	int *startOfData;
	int *endOfData;
	char *titles;	

	currentSearch = setSearchTag("title");
	startOfData = search(file, currentSearch, "start");
	

	currentSearch = setSearchTag("/title");	
	endOfData = search(file, currentSearch, "end");
	
}

char* setSearchTag(char *search) {

	char *newSearchTag;
	char *startTag = "<";
	char *endTag = ">";
	int newSearchTagLength = strlen(search) + strlen(startTag) + strlen(endTag);	
	

	if ((newSearchTag = ( char * )malloc(sizeof(char) * (newSearchTagLength)+1)) == NULL){
		fprintf(stderr, "Unable to allocate %d bytes of memory for current search\n", newSearchTagLength+1);
		exit(1);
	}		

	strcpy(newSearchTag, startTag);
	strcat(newSearchTag,search);
	strcat(newSearchTag,endTag);

	return newSearchTag;
				
}

int* search(char *file, char *currentSearch, char *tagType) {

	int error = 0;
    regex_t re;
    size_t a = 2;
    regmatch_t arrayOfMatches[1000];
	int counter=0;
	int *Matches;
	    
    if (regcomp(&re, currentSearch, REG_EXTENDED|REG_ICASE) != 0) {

        return(0);      

    }

	if ((Matches = malloc(sizeof(int))) == NULL){
			fprintf(stderr, "Unable to reallocate %d bytes of memory for current search\n", sizeof(int));
			exit(1);
	}


	printf("-----XXXXXXXXXXXXXXXXXXXXXXXXXX-----\n");
    
	/* Finds the matches on the line */
	error = regexec (&re, file, a, arrayOfMatches, 0);

	/* while matches found */
	while (error == 0) {    
	 		
		if(strcmp(tagType,"start")){
			Matches[counter] = arrayOfMatches[counter].rm_eo;
		}
		
		else{
			Matches[counter] = arrayOfMatches[counter].rm_so;
		}

		if ((Matches = (int *)realloc(Matches, sizeof(int))) == NULL){
			fprintf(stderr, "Unable to reallocate %d bytes of memory for file\n", sizeof(int));
			exit(1);
		}
 		
  	  	/* This call to regexec() finds the next match */
    	error = regexec (&re, file + arrayOfMatches[counter].rm_eo, 1, arrayOfMatches, REG_NOTBOL);
    	
		counter++;
    }

	if (error == 0) {    
	
 		return 0;
    }
	
	regfree(&re);
    
    return Matches;

}

ok...ive fixed the problem in setSearchTag...i needed to use calloc instead of malloc....

but i now get a bus error in the search method above...gdb tells me its on the line where i do my realloc 'ing...which is odd cause i copyed from a textbook...any ideas ?:

Code:

if ((Matches = (int *)realloc(Matches, sizeof(int))) == NULL){
			fprintf(stderr, "Unable to reallocate %d bytes of memory for file\n", sizeof(int));
			exit(1);
		}

thats correct...each time i add something to the array...all i need is one int...
which is 1 element...isnt it?

thanks for all ur help ppl...i fixed all my memory problems