Thread: malloc problem

First thing is it should be

Code:

str=(char *)malloc(len*sizeof(char) + 1);

To account for the string termintor since strlen only returns the length of the string, which is the number of characters in a string minus the string terminator.

also

Code:

strncpy(str,url_str,len+1);

although personally i'd just use strcpy since you what to entire string to copy anyway.

I think your problem is that your freeing memory then trying to read from it.

the pointers in tmp and var point to characters in str, but your freeing str, then reading from it using tmp and var.

Hopefully that solves the problem

Would something like this -- a different approach -- do what you want?

Code:

#include <stdio.h>
#include <string.h>

struct sPair
{
   char *name;
   char *value;
};

void parse(char *url, struct sPair *pair, size_t size)
{
   char *ptr = url;
   for( ; size--; ++pair)
   {
      pair->name = strtok(ptr, "=");
      if(pair->name == NULL)
      {
         break;
      }
      else
      {
         if(ptr != NULL)
         {
            ptr = NULL;
         }
      }
      pair->value = strtok(ptr, "&");
      if(pair->value == NULL)
      {
         break;
      }
   }
}

int main(void)
{
   char url[] = "host=localhost&user=default";
   struct sPair pair[5] = {0};
   size_t i;
   parse ( url, pair, sizeof pair / sizeof *pair );
   for(i = 0; i < sizeof pair / sizeof *pair; ++i)
   {
      if(pair[i].name != NULL && pair[i].value != NULL)
      {
         printf("name = %s, value = %s\n", pair[i].name, pair[i].value);
      }
   }
   return 0;
}

/* my output
name = host, value = localhost
name = user, value = default
*/

If you want to avoid strtok, you can use something like this:

Code:

char szParams[] = "host=localhost&user=default"
BOOL bInValue;
char * szParamName;
char * szParamValue;

while (*szParams) {

	if (*szParams == '=' && !bInValue) {
		bInValue = TRUE;
		szParamValue = szParams + 1;  // Param value starts after the equal
		*szParams = '\0';            // Terminate param name at equal
	}
	else if (*szParams == '&' && bInValue) {
		bInValue = FALSE;
		*szParams = '\0';   // Terminate param value at ampersand
		szParamName = szParams + 1;  // Start new param name after ampersand

		printf("%s = %s", szParamName, szParamValue);
	}

	szParams++;  // Move to next character
}

// print last value - terminated by null, not '&'
if (bInValue) printf("%s = %s", szParamName, szParamValue);