My Replace function Works while debugging But not compiled file doesnot

_username's Avatar, Join Date: May 2008
Newbie Member
I made a Replace fuction that works while I debug (Vs 2005 ) the compiled file closes due to some some any help would be appreciated


this is my code
Code:
char* _replace(char* source_str,char* search_str,char* replace_str,char* ostr)
{
char *data = source_str;
char *orgdata = data;
int ser_sz = strlen(search_str);
int rep_sz = strlen(replace_str);
char _k = 0;
ostr = malloc(strlen(source_str));
ostr[0] = '\0';		/* remove garbage value */
if (rep_sz >= ser_sz){ _k = 1; } 
do{
  char *p = strstr(data,search_str);	/* get the pointer to the first occurrence */
	if (!p){ 
         strcat(ostr,orgdata);	/*append the rest*/
         break;
	}
	if (!_k) {
		realloc(ostr,(strlen(ostr) + rep_sz-ser_sz));
	}
  strncat(ostr,orgdata,p - orgdata);	/*append the rest of the string*/
  data = p + ser_sz;	/*ignore the search term*/
  strncat(ostr,replace_str,rep_sz);	/* place the replace string*/
  orgdata = p + ser_sz;	/* save the current data*/
  	}while(1);
   
return ostr;
}
0
_username's Avatar, Join Date: May 2008
Newbie Member
Okay ! i found a solution but its really awkward

I found that If I print some thing before I call the fuction it works good FOr example

Code:
 char *buffer = 0;
 char *strr = "LLkLLkbsbsbsbsbs";
 printf("_usename");
  buffer = _replace(strr,"LLk","LOLOLOLOLOLOLOLOLOLOLOLOLOLO :P",buffer);

 printf("%s",buffer);
 getchar();
THis one works but the following one doesn't

Code:
 char *buffer = 0;
 char *strr = "LLkLLkbsbsbsbsbs";
 /*printf("here");*/
  buffer = _replace(strr,"LLk","LOLOLOLOLOLOLOLOLOLOLOLOLOLO :P",buffer);

 printf("%s",buffer);
 getchar();
0
_username's Avatar, Join Date: May 2008
Newbie Member
I cannot find the Edit Sry ---

SO can any one explain what I am doing wrong pls
0
shabbir's Avatar, Join Date: Jul 2004
Go4Expert Founder
Edit button will come after you get your post count into double figures.
0
mr.anandc's Avatar, Join Date: May 2008
Go4Expert Member
Usage of return value of _replace(assigning to dest) should work fine
Code:
int main()
{
char search[] = "Hi";
char replace[] = "Bye";
char str[] = "HelloHiHelloHi";
char *dest;
dest = _replace(str, search, replace, dest);
printf("replaced string is %s\n", dest);
return 0;
}
Output of this is - HelloByeHelloBye. But if we directly use dest like below
Code:
_replace(str, search, replace, dest);
printf("replaced string is %s\n", dest);
this may result into segmentation fault. This is because "dest" is not initialized(not pointing) to any memory location. "dest" is passed as a value(not by pointer) and _replace function allocates memory locally and initializes it to local pointer(ostr - and this does not reflect to dest). On exit of _replace function ostr variable is deallocated and we lost the reference to allocated memory. So, it could result into memory leak too.

We should be careful when allocating memory in called function. It is good idea to always return the pointer to allocated memory. So the _replace specification becomes

Code:
char* _replace(char* source_str,char* search_str,char* replace_str) // last argument is removed
But still if the last argument is required then pass address of "dest" to _replace. Then specification becomes

Code:
char* _replace(char* source_str,char* search_str,char* replace_str,char** ostr) // type of ostr is changed to char**
and _replace function has to be updated accordingly(just replace ostr usage with *ostr) so that the change in ostr reflects to "dest" in callee function.

Hope this may help you.