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Work with matrix

wickedcro (2)
Hello guys,

I am a beginner in this domain, and I'm learning right now about 2d arrays that are dynamically allocated. I've already done this, a code that computes the sum of two matrix. I want to know if someone can give me some ideas about some codes that are doing the multiplication of two arrays
(only compatible dimensions), multiplication by scalar, the transposed matrix, and also a method to resize the matrix. I've google it so many times, and i don't want to think that the problem is me not understanding this elementary things. Have a nice day :)

PS:Sorry if my english is bad:)
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#include<iostream>
#include<iomanip>
#include<math.h>

using namespace std;

class matrix
{
		int row, col;	// array dim //
		double* m;		// pointer used //
	public:
		matrix(int =0, int =0);	
		matrix(const matrix&);		// copy constructor //
		~matrix();				// destructor //
		void read();
		void print();
		matrix& operator =(const matrix&);	
		matrix operator+(const matrix&);
		friend matrix operator-(const matrix&, const matrix&); 
		matrix operator*(const matrix&);	
		double max();
		};

matrix::matrix(int r, int c)
{
	row =r;
	col = c;
    m=new double[row*col];
    for(int i=0;i<row;i++)
		for(int j=0;j<col;j++)
			m[i*col+j]=0;
}

matrix::matrix(const matrix& mat)
{
	row =mat.row;
	col = mat.col;
    m=new double[row*col];
    for(int i=0;i<row;i++)
		for(int j=0;j<col;j++)
			m[i*col+j]=mat.m[i*mat.col+j];
}

matrix::~matrix()
{
	delete [] m;
}

void matrix::print()
{
	cout << fixed << setprecision(2);
	for(int i=0;i<row;i++)
	{ 
		for(int j=0; j<col; j++)
		{
			cout.width(8);
			cout<<m[i*col+j];
		}
		cout<<endl;
	}
}

void matrix::read()
{
for(int i=0;i<row;i++)
	for(int j=0;j<col;j++)
	{
		cout<<"\nelement ("<<i<<","<<j<<"): ";
		cin>>m[i*col+j];
	}
}

matrix matrix::operator +(const matrix& a)
{
	int i,j;
	matrix x(row>a.row? row: a.row , col>a.col? col : a.col);
	
	for( i=0;i<row;i++)
		for( j=0;j<col;j++)
			x.m[i*x.col+j]=m[i*col+j];
	for( i=0;i<a.row;i++)
		for( j=0;j<a.col;j++)
			x.m[i*x.col+j] += a.m[i*a.col+j];
	return x;
}

matrix& matrix::operator=(const matrix& y)
{
	if(row != y.row || col != y.col)
	{
		delete [] m;
		row = y.row;
		col = y.col;

		m = new double[row*col];
	}
	for(int i=0;i<row;i++)
		for(int j=0;j<col;j++)
			m[i*col+j]=y.m[i*y.col+j];
	return *this;
}

matrix matrix::operator-(const matrix& s)
{
	
int main()
{
	int r, c;
	cout<<"rows number = ";
	cin >> r;
	cout<<"columns number =	";
	cin >> c;

	matrix a(r,c);
	cout<<"\nread matrix a:\n" ;
	a.read();
	cout<<"\nmatrix a is:\n";
	a.print();
	matrix b(r, c);
	cout<<"\nread matrix b\n";
	b.read();
	cout<<"\nmatrix b is:\n";
	b.print();
	matrix s=a+b;
	cout<<"\nthe sum s = a+b is:\n";
	s.print();
	

	cin.ignore(100, '\n');
	cin.get();
}
closed account (48bpfSEw)
there are a lot of examples in the wide wide world... ^^

https://www.google.de/?client=firefox-b#q=c%2B%2B+matrix+multiplication&gfe_rd=cr

wickedcro (2)
i mean, if someone can help me in the way my code is written, this is the only way i learnt to dynamic allocate a matrix...
closed account (48bpfSEw)
Take this out of your code and the compiler is happy:

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// matrix matrix::operator-(const matrix& s)
// {
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