Not knowing what to do with this C++ assignment...

[madosenshi]

I'm a beginner and I know it's pathetic to post this on the board,

but I'm really desperate. I need to hand this til midnight I have still no

clue what to fill in the blanks. It's about matrices but I didn't learn C++

a lot so I'm stuck. Would you guys help me?

Here's the header file

 
#ifndef MATRIX_H
#define MATRIX_H
#include <iostream>

class Matrix
{
public
Matrix(int a=0, int b=0, int c=0, int d=0);
~Matrix() {}
void ShowMatrix();
Matrix Transpose();
Matrix operator+(const Matrix& a);
Matrix operator-(const Matrix& a);
Matrix operator*(const Matrix& a);
void operator=(const Matrix& a);

private:
int m[2][2];
};

#include "Matrix.h"
Matrix::Matrix(int a, int b, int c, int d)
{ blank }

Matrix Matrix::Transpose()
{ blank }

Matrix Matrix::operator+(const Matrix &a)
{ blank }

Matrix Matrix::operator-(const Matrix &a)
{ blank }

Matrix Matrix::operator*(const Matrix &a)
{ blank }

void Matrix::operator=(const Matrix &a)
{ blank }

void Matrix::ShowMatrix()
{ blank }

I hate myself... what's worse is that I have to make a cpp file that has 3x3 matrix.

[rodiongork]

About "what to do"

It's about matrices but I didn't learn C++

It's clear - simply start learning C++ right now. You need not learn too much for this simple task, so cheer up.

Since it is assignment which proposes that you should learn - you should, so cheer up. Many people struggled through this successfully.

See, here is a tutorial

http://www.cplusplus.com/doc/tutorial/

Though you perhaps will found something more suitable for you.

Here are some simpler tasks by which you can have enough practice:

http://codeabbey.com/

I need to hand this til midnight

It looks you'll need to ask an allowance for week more...

[NGangst]

Hi Madosenshi,

there is nothing pathetic about asking for help, its why this forum is here after all (:

The first question is, are you familiar with matrices ? obviously if you haven't covered that this task will not make any sense, if you have covered matrices, most of what is being asked for here should be fairly easy:

To start with the constructor:

all it needs to do is populate the internal array of integers from the values passed in:

Matrix::Matrix(int a, int b, int c, int d)
{
  m[0][0]  =a;
  m[0][1]  =b;
  m[1][0]  =c;
  m[1][1]  =d;
}

these:

Matrix operator+(const Matrix& a);
Matrix operator-(const Matrix& a);
Matrix operator*(const Matrix& a);
void operator=(const Matrix& a);

are operator overloads; if someone uses your library to define two matrices and wishes to add them together, you as a programmer, need to explain to the compiler what an "add" between two "Matrices" is:

Matrix matrix_a(1, 2, 3, 4);
Matrix matrix_b(4, 3, 2, 1);
Matrix matrix_c = matrix_a+matrix_b;

in this situation the overloaded + operator within matrix_a would receive a constant referance to matrix_b.

thus inside the +operator definition you need to write some code to add all of the elements within the array "m" of the two matrices together, use those values to create a new matrix and then return it, so it can be used:

Matrix Matrix::operator+(const Matrix &a)
{ 
   int val_0_0 =m[0][0];
   int val_0_1 =m[0][1];
   int val_0_2 =m[1][0];
   int val_0_3 =m[1][1];

   int val_1_0 =a.m[0][0];
   int val_1_1 =a.m[0][1];
   int val_1_2 =a.m[1][0];
   int val_1_3 =a.m[1][1];


 Matrix return_matrix(val_0_0+val_1_0,
                                  val_0_1+val_1_1,
                                  val_0_2+val_1_2, 
                                  val_0_3+val_1_3  )

}

the remaining functions should be very similar, and a 3v3 matrix class is at least 90% identical to this one.

I hope this helps

Thanks - NGangst