Thread: Do I need to delete[] this?

Hey guys! Take a look at the code below:

Code:

char* c;
c = "asdf";
delete[] c;   //<-----

Do I need to include the line with the pointy arrow?

no and you also need to fix the code too....
look

char* p; // give me a pointer (could point anywhere)
c="asdf"; // note this is assignment not initialization. You cannot assign strings this way.You need to do this...
strcpy(p,"asdf");
now this has brought us a new problem. We have just written onto memory we dont own.

one quick fix is to turn assignment into initialisation by doing this...

char* p="asdf";
Now you have a pointer to a statically allocated string. You do not need call delete or delete[] on it because the memory used was controlled by the compiler and not you with new or new[].

personally i dont like static strings, because they're static .
what if you want to change them?
use globalalloc() or malloc(), its much more versatile.

Ok, thanks But I have no problem with static allocated strings, 'cuz it's for a help thing You know, go to help then controls.

if you use [] with your new then use [] with the delete.

example.

char *string=new char[20];
delete [] string;

CEmployee *emp=new CEmployee;
delete emp;

Ok But that wasn't my question; I know that perfectly well.
But what happens when I do this? (well, someone already answered, but you can ponder my original post anyways.)

Code:

char* c;
c = "asdf";
delete[] c;

Oh yeah, stonedcoder... What do you mean by "you can't assign strings this way"? That's how I had it in my code, and it compiled/ran fine. Unless, of course, you mean that I've written onto memory I don't own, like you said with strcpy() Could you clarify a bit?

>But what happens when I do this?

It will behave weird. If you are lucky, it crashes your app.

Reasons are listed above.

Hmm, so I've heard. But I recall seeing on another thread (I think it was in the C programming forum) Fordy recommending this method to some other guy... a slip of mind? (And besides, it seems to work fine for me! )

Or maybe I just remembered wrong...

Originally posted by Hunter2
Hmm, so I've heard. But I recall seeing on another thread (I think it was in the C programming forum) Fordy recommending this method to some other guy... a slip of mind? (And besides, it seems to work fine for me! )

Or maybe I just remembered wrong...

Yeah, but I certainly didnt call delete on it!

It may work now for you, but in time could blow up in your face.

To clarify a little on one point raised here (not related to delete)... this

Code:

char* c;
c = "asdf";

is perfectly valid. A use of it might be:

Code:

char *GetErrorText(int ErrorCode)
{
    char *p;
    
    switch (ErrorCode)
    {
        case   1: p = "Open failed";   break;
        case   2: p = "Close failed";  break;
        default : p = "Unknown error"; break;
    }
    
    return p;
}

Of course, you can't change the contents of the string literal at run time though.

Originally posted by Hammer

Code:

char* c;
c = "asdf";

is perfectly valid. A use of it might be:

goto is perfectly valid, too. But it is not recommended.

>goto is perfectly valid, too. But it is not recommended.
Different kettle of fish altogether...