I want to split a 3X3 matrix/array into 5 2X2 matrices. I am getting the following error. Please help.

Question

1.00/5 (1 vote)

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This is the error I am getting.

Error (active) E0167 argument of type "int" is incompatible with parameter of type "int (*)[3]"

What I have tried:

This is my code. The error line is highlighted in italics.

C++

#include<iostream>
#include<conio.h>
#include<math.h>

using namespace std;

int main()
{
	int n;
	int m[3][3];
	int i, j;
	cout << " Enter 1 or 0 for respective places" << endl;
	for (i = 0; i < 3; i++)
	{
		for (j = 0; j < 3; j++)
		{
		fg:
			cout << " Enter the Element for m[" << i << "][" << j << "]" << endl;
			cin >> m[i][j];
			if (m[i][j] != 1 && m[i][j] != 0)
			{
				cout << "This entry isnt allowed. ReEnter" << endl;
				goto fg;
			}
		}
	}
	cout << "the matrix is:" << endl;
	for (i = 0; i < 3; i++)
	{
		for (j = 0; j < 3; j++)
		{
			cout << "\t" << m[i][j];
		}
		cout << "\n";
	}

	X3(m[3][3]);    ###Error Line###
	return 0;
}

int X3(int m[3][3]) //generation of new matrices for 3X3 matrix
{
	int x[2][2];
	int i, j;
	int a, b;
	for (i = 0; i < 3 ; i++)
	{
		for (j = 0; j < 3; j++)
		{
			x[0][0] = m[i][i+j];
			x[0][1] = m[i][i + j + 1];
			x[1][0] = m[i + 1][i + j];
			x[1][1] = m[i + 1][i + j + 1];

			cout << " The newly generated matrices are:" << endl;

			for (a = 0; a < 2; a++)
			{
				for (b = 0; b < 2; b++)
				{
					cout << "\t" << x[a][b];
				}
				cout << "\n";
			}
			
		}
	}
}

Posted 21-Mar-22 23:39pm

Atharav Jadhav

Updated 21-Mar-22 23:55pm

CPallini

v2

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3 solutions

Solution 3

When you declare an array as a function parameter:

C++

int X3(int m[3][3]
{
   ...
}

You are telling the compiler that X3 accepts a single parameter, which is a 3 x 4=3 array of integers.

When you call a function with a parameter like this:

C++

X3(m[3][3]);

You are dereferencing the array to a single element of that array - which actually lies outside the bound of the array itself:

C++

int m[3][3];

because in C++, array indexes start at zero.
The dereference is the same as assigning a variable:

C++

int x = m[0][[0];

Puts the value in the first element of the first row of the array m into x

There are numerous problems with that code that you haven' noticed yet, including (but not limited to):
* X3 does not retrun a value.
* if you returned the "new array" x from X3 you would have a dangling reference, and your code would start to behave very badly - you can't return stack based items and expect it to work properly!
* why are you looping and using constant values in X3?

That code doesn't look "Planned" - it looks like you quickly scanned teh take and leapt into code without thinking about what you are expected to do - and it shows as poor code that really isn't worth saving. Back that up somewhere, and start again from scratch - read the assignment carefully, and think about how to solve it for five or ten minutes before you even start l=thinking about code. It'll save you loads of time in the long run!

Posted 21-Mar-22 23:52pm

OriginalGriff

Comments

Atharav Jadhav 22-Mar-22 6:06am

Thank you so much sir for your thoughtful insight and your invested time. I really respect your advice and will certainly act upon them.

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CPallini · Accepted Answer · 2022-03-21T23:55:00

Try

C++

#include <iostream>
#include <cmath>

using namespace std;

int X3(int m[][3]); //generation of new matrices for 3X3 matrix

int main()
{
  int m[3][3];
  int i, j;
  cout << " Enter 1 or 0 for respective places" << endl;
  for (i = 0; i < 3; i++)
  {
    for (j = 0; j < 3; j++)
    {
      bool bad_entry;
      do
      {
        cout << " Enter the Element for m[" << i << "][" << j << "]" << endl;
        cin >> m[i][j];
        bad_entry = (m[i][j] != 1) && (m[i][j] != 0);
        if ( bad_entry )
        {
          cout << "This entry isnt allowed. ReEnter" << endl;
        }
      } while ( bad_entry );
    }
  }
  cout << "the matrix is:" << endl;
  for (i = 0; i < 3; i++)
  {
    for (j = 0; j < 3; j++)
    {
      cout << "\t" << m[i][j];
    }
    cout << "\n";
  }

  X3(m);
  return 0;
}

int X3(int m[][3]) //generation of new matrices for 3X3 matrix
{
  int x[2][2];
  int i, j;
  int a, b;
  for (i = 0; i < 3 ; i++)
  {
    for (j = 0; j < 3; j++)
    {
      if ( ((i + j + 1)  < 3) && (i+1) < 3)
      {
        x[0][0] = m[i][i+j];
        x[0][1] = m[i][i + j + 1];
        x[1][0] = m[i + 1][i + j];
        x[1][1] = m[i + 1][i + j + 1];

        cout << " The newly generated matrices are:" << endl;

        for (a = 0; a < 2; a++)
        {
          for (b = 0; b < 2; b++)
          {
            cout << "\t" << x[a][b];
          }
          cout << "\n";
        }
      }
    }
  }
  return 0;
}

Richard MacCutchan · Accepted Answer · 2022-03-21T23:50:00

Solution 2

You are trying to pass a single integer (1. m[3][3]) to a function that is expecting an array (2. m[3][3]).

1. At this point the call to X3 says pass the single integer at row 3, column 3 of m to the function X3.
2. In your definition of the function X3 you declare parameter 1 to be an array of int types with 3 rows and 3 columns.

Your call to X3 should just pass the address of the array:

C++

X3(m);

Posted 21-Mar-22 23:50pm

Richard MacCutchan

Comments

Richard Deeming 22-Mar-22 6:06am

Looks like you've managed to post the same solution twice. :)

Richard MacCutchan 22-Mar-22 6:34am

No idea how that happened, although it did take a long time to come back.