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Using Vector::At doesn't initialize implicit types [message #17104]

Tue, 29 July 2008 10:51

cbpporter is currently offline

cbpporter
Messages: 1401
Registered: September 2007

Ultimate Contributor

If I use At or SetLength, Vecor will call the default constructor for the new items created which are not manually initialized for user classes, but will leave implicit types uninitialized.

Example:

#include <Core/Core.h>

using namespace Upp;

struct Foo: public Moveable<Foo>
{
	int x;
	
	Foo()							{ x = 0; }
	Foo(int xx) 					{ x = xx; }
};

CONSOLE_APP_MAIN
{
	Vector<int> v;
	v.At(0) = 7000;
	v.At(2) = 7000;
	
	DUMP(v[0]);
	DUMP(v[1]);
	DUMP(v[2]);
	
	Vector<Foo> w;
	w.At(0) = Foo(7000);
	w.At(2) = Foo(7000);
	
	DUMP(w[0].x);
	DUMP(w[1].x);
	DUMP(w[2].x);
}

I think we should change this. It can lead to problems and nasty crashes if you have a Vector<Foo>, where Foo is a value type class, and for some reason you need to start using Vector<Foo*>. If you Vector is not initialized in order, which is not a requirement for this class, you will most likely get memory corruption when you try to access the gaps and you cant test for NULL either.

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[Message index]

		Using Vector::At doesn't initialize implicit types By: cbpporter on Tue, 29 July 2008 10:51
		Re: Using Vector::At doesn't initialize implicit types By: mr_ped on Tue, 29 July 2008 10:52
		Re: Using Vector::At doesn't initialize implicit types By: cbpporter on Tue, 29 July 2008 11:10
		Re: Using Vector::At doesn't initialize implicit types By: mr_ped on Tue, 29 July 2008 11:13
		Re: Using Vector::At doesn't initialize implicit types By: cbpporter on Tue, 29 July 2008 11:20
		Re: Using Vector::At doesn't initialize implicit types By: mirek on Tue, 29 July 2008 11:24
		Re: Using Vector::At doesn't initialize implicit types By: cbpporter on Tue, 29 July 2008 16:03
		Re: Using Vector::At doesn't initialize implicit types By: mirek on Tue, 29 July 2008 18:39
		Re: Using Vector::At doesn't initialize implicit types By: cbpporter on Tue, 29 July 2008 21:55
		Re: Using Vector::At doesn't initialize implicit types By: mr_ped on Tue, 29 July 2008 11:22

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