Vector question

This is a discussion on Vector question within the C++ Programming forums, part of the General Programming Boards category; Hello, I have created a vector of pointers. If I resize my vector, will it be filled in with NULL ...

  1. #1
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    Feb 2010
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    Vector question

    Hello, I have created a vector of pointers.
    If I resize my vector, will it be filled in with NULL values?
    Or will it point to garbage? If it will point to garbage, how do I init them on NULL?

    Code:
    vector< vector< Tile*> > board;
    
    board.resize(size);
    
    for (int i = 0; i < size; i++)
         board[i].resize(size);
    This does not work because I am pointing to the values:

    Code:
         for(int i =0; i < size; i++)
         {
             for(int j=0; j < size; j++)
             {
                 board[i][j] = NULL;
             }
         }
    Thank you

  2. #2
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    push_back

    You could try using the push_back() method, and I know that int vectors are set to default value of 0, so maybe?

  3. #3
    Registered User whiteflags's Avatar
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    You should be supplying the other argument to resize()

    board[i].resize(size, NULL);

  4. #4
    C++まいる!Cをこわせ!
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    I believe that if you resize a vector, all of the values will be default-constructed, so that would mean NULL, yes.
    However, whiteflags has a point. You shouldn't be using resize anyway, unless you have a very specific requirement. Use push_back, and if possible, don't use pointers.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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