C++, Convert 1D Array into 2D Array

Question

I need to convert code that is currently using two functions to create a character 2D Array into one function that creates a character 2D Array.

The contents of the Array is the alphabet from 'A' to 'Y' (omitting 'Z', as I need a matrix of 5*5 size). Notes: I cannot use vectors or pointers.

The below code works, but it needs to be converted into one function, which I am having considerable trouble doing. I have been researching but I cannot find a clear enough solution, and I am a beginner in C++.

// Fills 4-Square Matrix 1 with Alphabet (1D Array)
void fill4Square1(char* FourSquare_1_Matrix)
{
    int n;
    for (n = 0; n < 25; n++)
        FourSquare_1_Matrix[n] = 'A' + n;
}
// Fills 4-Square Matrix 1 with Alphabet (2D Array)
void fill4Square1_1()
{
    char FourSquare_1_Matrix[5][5];
    fill4Square1((char*)FourSquare_1_Matrix); //Function Call for 1D Array
    for (int row = 0; row < 5; row++) //For Loop puts 1D array into 2D Array
    {
        for (int col = 0; col < 5; col++)
            cout << FourSquare_1_Matrix[row][col] << " ";
        cout << "\n";
    }
}

I wrote the below code, but I cannot get the contents of the 1D Array into the 2D array. The 2D Array is being filled with random char characters. Program OUTPUT

void PlayFairMatrix1()
{
    int i = 0;
    char Matrix[25] = { {0} };
    char PlayFairMatrix[5][5] = { {0} };
    int n;

    //1D Matrix
    for (i = 0; i < 25; i++)
    {
        Matrix[i] = 'A' + i;
        cout << Matrix[i];
    }
    cout << "\n";   
    cout << " " << endl;

    ////2D Matrix
    for (int row = 0; row < 5; row++)
    {
        for (int col = 0; col < 5; col++)
        {
            PlayFairMatrix[row][col] = Matrix[i];
                i++;
        }
        cout << PlayFairMatrix << " ";
        cout << "\n";
    }
    cout << " " << endl;

}

Can anyone please help point me in the right direction?

lamandy · Accepted Answer · 2017-12-11 00:50:33Z

1

The problem lies on this line PlayFairMatrix[row][col] = Matrix[i];

i starts off with the value 25 from previous loop. And you never reset it back to 0.

So, the simplest way to fix it is just add i = 0; before the second loop.

Another way will accessing Matrix using row and col, but I will leave that for you as an exercise.

Also, when you print PlayFairMatrix, you are not accessing it with index so you will print the pointer instead. You should put cout << PlayFairMatrix << " "; into inner loop and add the index, so it becomes cout << PlayFairMatrix[row][col] << " ";

edited Dec 11, 2017 at 0:50

answered Dec 11, 2017 at 0:45

lamandy

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2 Comments

mplh2008 Over a year ago

I tried resetting i back to zero i = 0 at the beginning of the 2nd loop and before the 3rd loop, and the output does not seem to be affected.

mplh2008 Over a year ago

Yes, and the code is working now - Thank you for your help, I really appreciate it.

Steephen · Accepted Answer · 2017-12-11 00:54:52Z

1

While populating PlayFairMatrix, you forgot to reinitialize variable i = 0. That will fix your code.

But you can do it simply as follows

void PlayFairMatrix1()
{
    char PlayFairMatrix[5][5] = { {0} };
    int i = 0;
    for(int row = 0; row < 5; ++row)
    {
       for(int col = 0; col < 5: ++col)
       {
           PlayFairMatrix[row][col]='A'+i;
       }
    }
}

answered Dec 11, 2017 at 0:54

Steephen

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1 Comment

mplh2008 Over a year ago

Thank you for your help. After resetting i = 0; and moving << cout << PlayFairMatrix[row][col] << " "; into the inner loop, the code works.

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