Returning char* from a function - GameCreators Forum

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Michael P

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Location: London (UK)

Posted: 21st Aug 2008 21:42

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+ Code Snippet

char * Function()
{
	char * CharArray;
	CharArray = new char[6];
	return(CharArray);
}

int main()
{
	char * Returned = Function();

	// I don't want to have to deallocate the memory
	delete[] Returned;

	return(0);
}

Is there a way that I can return char* without having to deallocate the memory once returned?

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Benjamin

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Posted: 21st Aug 2008 21:56

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You can use a static pointer:

+ Code Snippet

char * Function()
{
	static char * CharArray = new char[6];
	return(CharArray);
}

int main()
{
	char * Returned = Function();

	return(0);
}

But note that it won't return a unique buffer each time it is called, as it uses the same memory every time. Alternately, use std::strings or have the function accept a char* as an argument, and write to this instead.

Multisync - TCP Server/Client Multiplayer Plugin (DBP/DBCe)

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Michael P

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Posted: 21st Aug 2008 22:07

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On a related topic:

Are we supposed to delete memory for char* from DGDK commands like dbInput or are they returning static pointers?

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IanM

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Posted: 21st Aug 2008 23:27

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You need to delete the pointer when you are done. Just use 'delete[] Ptr;' to do the job.

[b]Utility plug-ins collection (updated 01/07/08) and
http://www.matrix1.demon.co.uk

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Zotoaster

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Posted: 22nd Aug 2008 16:42

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You could also use the auto_ptr class found in <memory>. It gives you automatic garbage collection IIRC.

+ Code Snippet

// Braces to scope the ptr
{
    auto_ptr<int> MyInt;   // Allocates a new int
}

cout << *MyInt << "\n";   // Error

I think that's how it works, though I'm not sure.

Don't you just hate that Zotoaster guy?

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Lilith

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Posted: 22nd Aug 2008 17:08

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But isn't MyInt out of scope by the time you try to use it in your cout statement?

Lilith, Night Butterfly
I'm not a programmer but I play one in the office

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IanM

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Posted: 22nd Aug 2008 20:55

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Apart from Zotoaster's coding problems

the other problem with auto_ptr is that it doesn't work correctly with arrays - it will only call the destructor of the first item in the array. That said, it would probably work for a plain type or a POD type, but it's technically undefined behaviour.

If you decide that RAII is the route to go, then the boost shared_array or scoped_array pointer types are the safest I know of.

[b]Utility plug-ins collection (updated 01/07/08) and
http://www.matrix1.demon.co.uk

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Zotoaster

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Posted: 23rd Aug 2008 19:53

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Quote: "But isn't MyInt out of scope by the time you try to use it in your cout statement?"