Why is this happening?

This is a discussion on Why is this happening? within the C++ Programming forums, part of the General Programming Boards category; Code: #include <iostream> int main() { int lines; int columns; std::cout << "lines: "; std::cin >> lines; std::cout << "columns: ...

  1. #1
    Registered User
    Join Date
    Jan 2005
    Posts
    204

    Why is this happening?

    Code:
    #include <iostream>
    
    int main()
    {
        int lines;
        int columns;
        
        std::cout << "lines: ";
        std::cin >> lines;
        
        std::cout << "columns: ";
        std::cin >> columns;
        
        int *matrix1 = new int[lines * columns]; 
        
        for (int i = 0; i < lines; i++)
            for (int j = 0; j < columns; j++) {
                std::cout << "matrix1[" << i << "][" << j << "]: ";
                std::cin >> matrix1[i * j + j];
            }
        
        for (int i = 0; i < lines; i++)
            for (int j = 0; j < columns; j++)
                std::cout << matrix1[i * j + j] << std::endl;
        
        delete [] matrix1;
    }
    If I type
    1
    2
    3
    4
    5
    6
    7
    8
    9

    I get
    7
    2
    5
    7
    5
    6
    7
    8
    9


  2. #2
    aoeuhtns
    Join Date
    Jul 2005
    Posts
    581
    Quote Originally Posted by caduardo21
    Code:
    matrix1[i * j + j]
    Don't you mean
    Code:
    matrix1[i * columns + j]
    in both cases?

  3. #3
    Code Goddess Prelude's Avatar
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    Posts
    9,796
    >Rashakil Fol
    That name looks familiar. Daniweb?
    My best code is written with the delete key.

  4. #4
    aoeuhtns
    Join Date
    Jul 2005
    Posts
    581
    Yes.

    Well isn't this a contentless post.

  5. #5
    C/C++Newbie Antigloss's Avatar
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    212
    here is another contentless post
    in my hometown, we mean contentless post by saying "pour water"

  6. #6
    Dae
    Dae is offline
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    hmm....
    Warning: Have doubt in anything I post.

    GCC 4.5, Boost 1.40, Code::Blocks 8.02, Ubuntu 9.10 010001000110000101100101

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