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Static vector losing its contents

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Join Date: Oct 2009

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Static vector losing its contents

Nov 9th, 2009

Hi guys,

I have a static vector which holds objects of a class. I want this vector to be singleton i.e. be the only vector of this type which will indefinitely store the relevant objects.

Unfortunately, a problem arises whereby, when I access the vector from a different class, for some reason it "loses" it's contents and is empty?

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Nearly a Posting Virtuoso

Nov 9th, 2009

>>a problem arises whereby, when I access the vector from a different class, for some reason it "loses" it's contents and is empty?
<<

From what content?

How about you make a adapter class, that wraps vector, and make that
adapter class singleton.

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1) Prove that the area of a circle is pi*r^2, where "r" is the radius of the circle.
2) Problem 2[b]solved by : jonsca

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Join Date: Oct 2009

Posts: 54

Reputation: pac-man is an unknown quantity at this point

Solved Threads: 3

pac-man

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Nov 9th, 2009

Hi there and thanks for the response. In the program, I navigate to an 'add book' GUI panel (A) which adds books to the vector. I then want to navigate to another panel (B) and populate a combobox using the contents of the vector. The vector remains populated in panel A but not B.

In short,
Home->Panel A->Home->Panel A the vector is fine
Home->Panel A->Home->Panel B then the vector appears empty

I tried to wrap the vector in a singleton class before trying to access the vBooks vector through the class as follows:

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 C++ Syntax (Toggle Plain Text) 
class SingletonVector
{
public:
	static vector<Book> vBooks;
	SingletonVector() {};
 
};
class SingletonVector
{
public:
	static vector<Book> vBooks;
	SingletonVector() {};
                     
};

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 C++ Syntax (Toggle Plain Text) 
SingletonVector sv;
Book b;
b.setTitle("Test title");
sv->vBooks.push_back(b); // PROBLEM LINE
SingletonVector sv;
Book b;
b.setTitle("Test title");
sv->vBooks.push_back(b); // PROBLEM LINE

The code compiles fine apart from when I use the function 'push_back' which results in the following error:

error LNK2001: unresolved external symbol "public: static class std::vector<class Book,class std::allocator<class Book> > SingletonVector::vBooks" (?vBooks@SingletonVector@@2V?$vector@VBook@@V?$allocator@VBook@@@std@@@std@@A)
vc_mswd\myapp.exe : fatal error LNK1120: 1 unresolved externals

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Join Date: Dec 2008

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Reputation: firstPerson is just really nice

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firstPerson firstPerson is online now

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Nov 9th, 2009

use SingletonVector::vBooks.push_back(b);

Help with Code Tags

(Toggle Plain Text)

1) Prove that the area of a circle is pi*r^2, where "r" is the radius of the circle.
2) Problem 2[b]solved by : jonsca

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Join Date: Oct 2009

Posts: 54

Reputation: pac-man is an unknown quantity at this point

Solved Threads: 3

pac-man

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Junior Poster in Training

Nov 9th, 2009

Still no go..feels like the fix is not much further!

MainFrame.obj : error LNK2001: unresolved external symbol "public: static class std::vector<class Book,class std::allocator<class Book> > SingletonVector::vBooks" (?vBooks@SingletonVector@@2V?$vector@VBook@@V?$allocator@VBook@@@std@@@std@@A)
Reports.obj : error LNK2001: unresolved external symbol "public: static class std::vector<class Book,class std::allocator<class Book> > SingletonVector::vBooks" (?vBooks@SingletonVector@@2V?$vector@VBook@@V?$allocator@VBook@@@std@@@std@@A)
vc_mswd\myapp.exe : fatal error LNK1120: 1 unresolved externals