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vectore problems again

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Started by Sync Views February 22, 2008 05:19 AM

4 comments, last by MaR_dev 16 years, 2 months ago

Sync Views

139

Author

February 22, 2008 05:19 AM

Why does this not work when the 2nd one does?


	for (std::vector<object*>::iterator it = object_list_depth.end(); it != object_list_depth.begin(); it--)
		if((*it)!=NULL && (*it)->active) (*it)->draw();//Vector iterator is not dereferencable


		for (std::vector<object*>::iterator it = object_list_depth.begin(); it != object_list_depth.end(); it++)
			if((*it)!=NULL && (*it)->active) (*it)->draw();

RIZAX

127

February 22, 2008 05:28 AM

stl vector's end method returns 1 pass the end of the list, so the first deference isn't actually returning anything in the list, try using:

for (std::vector<object*>::iterator it = object_list_depth.end()-1; it != object_list_depth.begin(); it--)		if((*it)!=NULL && (*it)->active) (*it)->draw();//

Sync Views

139

Author

February 22, 2008 05:34 AM

...vc\include\vectorLine: 163Expression:("_Myptr + _Off <= ((_Myvec *)(this->_Getmycount()))->_Mylast&&_Myptr+_off >=((_Myvec *)(this->Getmycount()))->_Myfirst",0)

	for (std::vector<object*>::iterator it = object_list_depth.end()-1; it != object_list_depth.begin(); it--)//HERE		if((*it)!=NULL && (*it)->active) (*it)->draw();

ToohrVyk

1,596

February 22, 2008 05:49 AM

Don't.

The operation v.end() - 1 will obviously fail on an empty vector. Instead of making life hard for yourself using normal iterators, use std::vector::rbegin and std::vector::rend.

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RIZAX

127

February 22, 2008 05:49 AM

you could also try using a reverse_iterator ... so:(check that syntax though I don't have an IDE in front of me)

for (std::vector<object*>::reverse_iterator it = object_list_depth.begin(); it != object_list_depth.end(); it++)
if((*it)!=NULL && (*it)->active) (*it)->draw();

MaR_dev

154

February 22, 2008 06:28 AM

for (std::vector<object*>::reverse_iterator it = object_list_depth.rbegin(); it != object_list_depth.rend(); it++)
if((*it)!=NULL && (*it)->active) (*it)->draw();

EDIT: note just fixed RIZAXs example, he forgot to add those 'r's.

[Edited by - MaR_dev on February 22, 2008 6:28:40 AM]

vectore problems again

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vectore problems again

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