dynamic memory allocation

This is a discussion on dynamic memory allocation within the C++ Programming forums, part of the General Programming Boards category; this is the question; Write a function that builds a two-dimensional multiplication table with arbitrary sizes for the two dimensions. ...

  1. #1
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    Mar 2013
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    36

    dynamic memory allocation

    this is the question; Write a function that builds a two-dimensional multiplication table with arbitrary sizes for the
    two dimensions.

    This is what I have done. I have allowed the user to input whatever size table they want by arbitrarily choosing what value they can input. However I cannot get the board to have blank squares. I thought the char would do it. Any suggestions? thanks

    Code:
    #include <iostream>
    
    
    using namespace std;
    
    
    char SQAURE_CHAR = {' '};
    
    
    const int Board_Size = 14;
    
    
    int main()
    {
    
    
        int **p_p_multtable;
    
    
        p_p_multtable = new int* [Board_Size];
    
    
        for (int i = 0; i < Board_Size; i++)
        {
            p_p_multtable[i] = new int [Board_Size];
        }
    
    
        for (int i = 0; i < Board_Size; i++)
        {
            for (int j = 0; j < Board_Size; j++)
            {
              p_p_multtable[i][j] = SQAURE_CHAR;
            }
        }
    
    
        for (int i = 0; i < Board_Size; i++)
        {
            delete [] p_p_multtable[i];
        }
    
    
        for (int i = 0; i < Board_Size; i++)
        {
            for (int j = 0; j < Board_Size; j++)
            {
              cout << p_p_multtable[i][j];
              if (j!= Board_Size - 1)
              {
                  cout << " | ";
              }
            }
            cout << endl;
            if (i != Board_Size - 1)
            {
                cout << "----------------------------" << endl;
            }
        }
        return 0;
    }

  2. #2
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    sorry noticed some mistakes changed the int to char but still not getting a blank board. below is rectified code.

    Code:
    #include <iostream>
    
    
    using namespace std;
    
    
    char SQAURE_CHAR = {' '};
    
    
    const int Board_Size = 14;
    
    
    int main()
    {
    
    
        char **p_p_multtable;
    
    
        p_p_multtable = new char* [Board_Size];
    
    
        for (char i = 0; i < Board_Size; i++)
        {
            p_p_multtable[i] = new char [Board_Size];
        }
    
    
        for (char i = 0; i < Board_Size; i++)
        {
            for (char j = 0; j < Board_Size; j++)
            {
              p_p_multtable[i][j] = SQAURE_CHAR;
            }
        }
    
    
        for (char i = 0; i < Board_Size; i++)
        {
            delete [] p_p_multtable[i];
        }
    
    
        for (char i = 0; i < Board_Size; i++)
        {
            for (char j = 0; j < Board_Size; j++)
            {
              cout << p_p_multtable[i][j];
              if (j!= Board_Size - 1)
              {
                  cout << " | ";
              }
            }
            cout << endl;
            if (i != Board_Size - 1)
            {
                cout << "----------------------------" << endl;
            }
        }
        return 0;
    }

  3. #3
    - - - - - - - - oogabooga's Avatar
    Join Date
    Jan 2008
    Posts
    2,808
    Why are you (partially) deleting the array before you print it???

  4. #4
    C++まいる!Cをこわせ! Elysia's Avatar
    Join Date
    Oct 2007
    Posts
    22,182
    You change all this maddening and ugly code...

    Code:
        char **p_p_multtable;
     
     
        p_p_multtable = new char* [Board_Size];
     
     
        for (char i = 0; i < Board_Size; i++)
        {
            p_p_multtable[i] = new char [Board_Size];
        }
     
     
        for (char i = 0; i < Board_Size; i++)
        {
            for (char j = 0; j < Board_Size; j++)
            {
              p_p_multtable[i][j] = SQAURE_CHAR;
            }
        }
     
     
        for (char i = 0; i < Board_Size; i++)
        {
            delete [] p_p_multtable[i];
        }
    ...to...

    Code:
    std::vector<std::vector<char>> multtable(Board_Size, std::vector<char>(SQUARE_CHAR));
    The delete is an error, btw. Don't free anything before you've finished using it. But with vector, you don't have to. It's automatic.
    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.
    For information on how to enable C++11 on your compiler, look here.
    よく聞くがいい!私は天才だからね! ^_^

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