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2D array Help

Inthemountainair (8)
So i have two 2d arrays and i need to add subtract and multiply them then display them. i have everything pretty much good but im not getting the correct answers and i cant seem to figure out why. also im having some trouble finding a good tutorial on how to multiply 2d arrays. 
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//****************************************************************************************************

#include<iostream>
#include<fstream>
#include<iomanip>
using namespace std;

void loadData(int matrix1 [4][4], int matrix2[4][4], int rows, int cols);
void addMatrices(int matrix1 [4][4], int matrix2[4][4], int result[4][4], int rows, int cols);
void subtractMatrix(int matrix1 [4][4], int matrix2[4][4], int result[4][4], int rows, int cols);
//void multiplyMatrix(int matrix1 [4][4], int matrix2[4][4], int result[4][4], int rows, int cols);
void outputData(int matrix1 [4][4], int matrix2[4][4], int rows, int cols);
void outputResult(int result[4][4], int resultType, int rows, int cols);

int main ()
{
    int rows,
        cols,
        resultType = 1,
        matrix1[4][4],
        matrix2[4][4],
        result[4][4];
        ifstream DataFile;
        ifstream Data2File;
        fstream OutputFile;
    
    loadData(matrix1, matrix2, rows, cols);
    outputData(matrix1, matrix2, rows, cols);
    addMatrices(matrix1, matrix2, result, rows, cols);
    outputResult(result, resultType, rows, cols);
    resultType = 2;
    subtractMatrix(matrix1, matrix2, result, rows, cols);
    outputResult(result, resultType, rows, cols);
    resultType = 3;
    //multiplyMatrix(matrix1, matrix2, result, rows, cols);
    //outputResult(result, resultType, rows, cols);
    
    return 0;
}

//****************************************************************************************************

void loadData(int matrix1 [4][4], int matrix2[4][4], int rows, int cols)
{
    cout << "Enter Data for Matrix 1" << endl;
    
    for (int rows = 0; rows < 4; rows++)
    {
        for (int col = 0; col < 4; col++)
        {
            cout << "row - " << rows + 1 << " colummn - " << col + 1 << " =  ";
            cin >> matrix1[rows][col];
        }
    }
    
    cout << endl << "Enter Data for Matrix 2" << endl;

    for (int rows = 0; rows < 4; rows++)
    {
        for (int col = 0; col < 4; col++)
        {
            cout << "row - " << rows + 1 << " colummn - " << col + 1 << " =  ";
            cin >> matrix2[rows][col];
        }
    }
    cout << endl;
}

//****************************************************************************************************

void addMatrices(int matrix1 [4][4], int matrix2[4][4], int result[4][4], int rows, int cols)
{
    for( int rows = 0; rows < 4; rows++)
    {
        for (int col = 0; col < 4; col++)
        {
            result[rows][col] = matrix1[rows][col] + matrix2[rows][cols];
        }
    }
}

//****************************************************************************************************

void subtractMatrix(int matrix1 [4][4], int matrix2[4][4], int result[4][4], int rows, int cols)
{
    for( int rows = 0; rows < 4; rows++)
    {
        for (int col = 0; col < 4; col++)
        {
            result[rows][col] = matrix1[rows][col] - matrix2[rows][cols];
        }
    }
}

//****************************************************************************************************

void outputData(int matrix1 [4][4], int matrix2[4][4], int rows, int cols)
{
    cout << "Matrix 1:" << endl;
    for (int rows = 0; rows < 4; rows++)
    {
        for (int col = 0; col < 4; col++)
        {
            cout << setw(6) << matrix1[rows][col];
            if (col == 3)
            {
                cout << endl;
            }
        }
    }
    cout << "Matrix 2;" << endl;
    for (int rows = 0; rows < 4; rows++)
    {
        for (int col = 0; col < 4; col++)
        {
            cout << setw(6) << matrix2[rows][col];
            if (col == 3)
            {
                cout << endl;
            }
        }
    }
}

//****************************************************************************************************

void outputResult(int result[4][4], int resultType, int rows, int cols)
{
    if (resultType == 1) {
        cout << "Addition Results" << endl;
    }
    if (resultType == 2) {
        cout << "Subtraction Results" << endl;
    }
    if (resultType == 3) {
        cout << "Multiplication Results" << endl;
    }
    
    for (int rows = 0; rows < 4; rows++)
    {
        for (int col = 0; col < 4; col++)
        {
            cout << setw(6) << result[rows][col];
            if (col == 3)
            {
                cout << endl;
            }
        }
    }
}

//****************************************************************************************************

and this is my output.
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Enter Data for Matrix 1
row - 1 colummn - 1 =  7
row - 1 colummn - 2 =  8
row - 1 colummn - 3 =  5
row - 1 colummn - 4 =  3
row - 2 colummn - 1 =  4
row - 2 colummn - 2 =  1
row - 2 colummn - 3 =  10
row - 2 colummn - 4 =  6
row - 3 colummn - 1 =  -2
row - 3 colummn - 2 =  12
row - 3 colummn - 3 =  2
row - 3 colummn - 4 =  9
row - 4 colummn - 1 =  1
row - 4 colummn - 2 =  5
row - 4 colummn - 3 =  4
row - 4 colummn - 4 =  6

Enter Data for Matrix 2
row - 1 colummn - 1 =  -3
row - 1 colummn - 2 =  6
row - 1 colummn - 3 =  4
row - 1 colummn - 4 =  7
row - 2 colummn - 1 =  2
row - 2 colummn - 2 =  1
row - 2 colummn - 3 =  8
row - 2 colummn - 4 =  3
row - 3 colummn - 1 =  5
row - 3 colummn - 2 =  -1
row - 3 colummn - 3 =  4
row - 3 colummn - 4 =  10
row - 4 colummn - 1 =  7
row - 4 colummn - 2 =  6
row - 4 colummn - 3 =  12
row - 4 colummn - 4 =  8

Matrix 1:
     7     8     5     3
     4     1    10     6
    -2    12     2     9
     1     5     4     6


Matrix 2;
    -3     6     4     7
     2     1     8     3
     5    -1     4    10
     7     6    12     8
Addition Results
     4     5     2     0
     6     3    12     8
     3    17     7    14
     8    12    11    13
Subtraction Results
    10    11     8     6
     2    -1     8     4
    -7     7    -3     4
    -6    -2    -3    -1
Program ended with exit code: 0
Any help would be greatly appreciated!!! Thank you
helios (17506)
Get rid of the ", int rows, int cols" parameters for your functions. The values you pass through them are not valid. After you do that, the compiler will generate some errors; this is because you accidentally used those meaningless values in your function bodies. Fix those uses to the correct variables and run the program again.
Inthemountainair (8)
Those were the function parameters that were given to me.
giblit (3750)
Maybe the rows/columns should be used instead of the arbitrary 4's? Otherwise it would be pointless. You might as well just create a temp variable like row/column or i/j?
Last edited on
Inthemountainair (8)
I went and replaced all the col with cols that I mistakingly threw in there and it works like a charm now.

heres the multiplication function that I worked out.
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void multiplyMatrix(int matrix1 [4][4], int matrix2[4][4], int result[4][4], int rows, int cols)
{
    int k;
    for (rows = 0; rows < 4; rows++)
    {
        for (cols = 0; cols < 4; cols++)
        {
            result[rows][cols] = 0;
            for (k = 0; k < 4; k++)
            result[rows][cols] = result[rows][cols] + (matrix1[rows][k]) * (matrix2[k][cols]);
        }
        cout<<endl;
    }
}
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