C++ Multi dimensional arrays

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Join Date: Oct 2007

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C++ Multi dimensional arrays

Oct 12th, 2007

I am very new to C++ and one of my homework assignments involvemulti dimensional arrays.

I was able to initialize and input and display the array (4x4) but the last step is to swap the data of the row to that of the column. Tried different ways and unable to figure out the code. Can you help?

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 #include<iostream>
#include<iomanip>
using namespace std;
int main()
{
    const int NO_OF_ROWS = 4;
    const int NO_OF_COLUMNS =4;
    int matrix[NO_OF_ROWS][NO_OF_COLUMNS];
int copyArray(int row,int col,int arraysize);
 
    int row;
    int col;
 
    //initialize 
 
    for (col = 0; col < NO_OF_COLUMNS; col++)
         matrix[NO_OF_ROWS][NO_OF_COLUMNS] = 0;
    for (row = 0; row < NO_OF_ROWS; row++)
         matrix[NO_OF_ROWS][NO_OF_COLUMNS] = 0;
 
    // print
 
      //Input
    cout << "Enter the 16 integers for data. " << endl;
    for (col = 0; col < NO_OF_COLUMNS; col++)
 
    for (row = 0; row < NO_OF_ROWS; row++)
 
        cin >> matrix[row][col];
 
 
        //print
        for (row = 0; row < NO_OF_ROWS; row++)
        {
            for (col = 0; col < NO_OF_COLUMNS; col++)
                cout << setw(5) << matrix[row][col] << " ";
                cout << endl;
        }
 
// swap contents of row to the column
 
    for(row = 0; row < NO_OF_ROWS-1; row--)
 
 
 
 
  // print
 int copyArray(int row,int col,int arraysize);
 
 
 
 
        {
            for (col = 0; col < NO_OF_COLUMNS; col++)
                cout << setw(5) << matrix[row][col] << " ";
                cout << endl;
        }
        //interchange rows and columns
 
    return 0;
}
 #include<iostream>
#include<iomanip>
using namespace std;
int main()
{
    const int NO_OF_ROWS = 4;
    const int NO_OF_COLUMNS =4;
    int matrix[NO_OF_ROWS][NO_OF_COLUMNS];
int copyArray(int row,int col,int arraysize);
     
    int row;
    int col;

    //initialize 
    
    for (col = 0; col < NO_OF_COLUMNS; col++)
         matrix[NO_OF_ROWS][NO_OF_COLUMNS] = 0;
    for (row = 0; row < NO_OF_ROWS; row++)
         matrix[NO_OF_ROWS][NO_OF_COLUMNS] = 0;
         
    // print
    
      //Input
    cout << "Enter the 16 integers for data. " << endl;
    for (col = 0; col < NO_OF_COLUMNS; col++)
        
    for (row = 0; row < NO_OF_ROWS; row++)
       
        cin >> matrix[row][col];
        

        //print
        for (row = 0; row < NO_OF_ROWS; row++)
        {
            for (col = 0; col < NO_OF_COLUMNS; col++)
                cout << setw(5) << matrix[row][col] << " ";
                cout << endl;
        }

// swap contents of row to the column

    for(row = 0; row < NO_OF_ROWS-1; row--)
    

    
 
  // print
 int copyArray(int row,int col,int arraysize);
     
        

    
        {
            for (col = 0; col < NO_OF_COLUMNS; col++)
                cout << setw(5) << matrix[row][col] << " ";
                cout << endl;
        }
        //interchange rows and columns
    
    return 0;
}

Last edited by WolfPack : Oct 12th, 2007 at 11:41 pm. Reason: Add Code Tags next time you post.

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Join Date: Aug 2005

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Re: C++ Multi dimensional arrays

Oct 12th, 2007

The code in lines 16-20 is all wrong. you need nested loops to do that, and array indices are the values of the loop counters, like this:

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array[row][col] = 0;

Or even easier -- you don't have to do the above at all if you initialize the array when it is declared

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int matrix[NO_OF_ROWS][NO_OF_COLUMNS] = {0};

Last edited by Ancient Dragon : Oct 12th, 2007 at 11:59 pm.

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Join Date: Oct 2007

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Re: C++ Multi dimensional arrays

Oct 13th, 2007

The compiler builds it and the output is ok. My problem is swapping the data from the column to the rows and displaying the new output. I've been working on this and still could not get it right.

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Re: C++ Multi dimensional arrays

Oct 13th, 2007

>>The compiler builds it and the output is ok
Yes the compiler will build it, but its not ok. What you have is called buffer overrun. Look at what you posted and THINK about it for a couple minutes. Why do I say buffer overrun -- because array element at indices matrix[NO_OF_ROWS][NO_OF_COLUMNS] does not exist. Your program is scribbling all over memory outside he boundries of the array.

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Join Date: Oct 2007

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Re: C++ Multi dimensional arrays

Oct 13th, 2007

I managed to get it!! Anyway, here's the code just in case someone comes along with the same question.
#include<iostream>
#include<iomanip>
using namespace std;
int main()
{
const int NO_OF_ROWS = 4;
const int NO_OF_COLUMNS =4;
int matrix[NO_OF_ROWS][NO_OF_COLUMNS];
int copyArray(int row,int col,int arraysize);
const int END_OF_ROW = 4;
const int END_OF_COL =4;
int row;
int col;

//initialize

for (col = 0; col < NO_OF_COLUMNS; col++)
matrix[NO_OF_ROWS][NO_OF_COLUMNS] = 0;
for (row = 0; row < NO_OF_ROWS; row++)
matrix[NO_OF_ROWS][NO_OF_COLUMNS] = 0;

// print

//Input
cout << "Enter the 16 integers for data. " << endl;
for (col = 0; col < NO_OF_COLUMNS; col++)

for (row = 0; row < NO_OF_ROWS; row++)

cin >> matrix[row][col];

//print
for (row = 0; row < NO_OF_ROWS; row++)
{
for (col = 0; col < NO_OF_COLUMNS; col++)
cout << setw(5) << matrix[row][col] << " ";
cout << endl;
}
for (col = 0; col < NO_OF_COLUMNS ; col++)
{
for (row = 0; row < NO_OF_ROWS ; row++)

;}
cout << endl;

for (row = 0; row < NO_OF_ROWS; row++)
{
for (col = 0; col < NO_OF_COLUMNS; col++)
cout << setw(5) << matrix[col][row] << " ";
cout << endl;
}

// print

return 0;

}