求矩阵的乘法

[MZJCDD]

#include<iostream.h>
#include<iomanip.h>
int a[3][4]={{4,1,2,5},
{5,2,1,3},
{2,4,5,7}};
int b[4][5]={{5,4,3,2,1},
{2,3,4,5,6},
{1,2,4,5,7},
{1,5,5,5,5}};
int c[3][5];
void main()
{ int c[3][5];
int i,j;
for( i=0;i<3;i++)
{ for( j=0;j<4;j++)
cout<<setw(3)<<a[i][j];
cout<<endl;
}
cout<<endl<<endl;
for( i=0;i<4;i++)
{ for( j=0;j<5;j++)
cout<<setw(3)<<b[i][j];
cout<<endl;
}
for( i=0;i<3;i++)
for( j=0;j<5;j++)
for(int k=0;k<4;k++)
c[i][j]+=a[i][k]*b[k][j];
for( i=0;i<3;i++)
{for(int j=0;j<5;j++)
cout<<setw(5)<<c[i][j];
cout<<endl;
}
}
怎么我的结果不对啊 ！请帮忙指点

[ryfdizuo]

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

int a[3][4]=
{
	{4,1,2,5}, 
	{5,2,1,3}, 
	{2,4,5,7}}; 

int b[4][5]={{5,4,3,2,1}, 
{2,3,4,5,6}, 
{1,2,4,5,7}, 
{1,5,5,5,5}}; 
int c[3][5]; 
void main() 
{ int c[3][5]={0};   //没有初始化；
int i,j;  
for( i=0;i <3;i++) 
{ for( j=0;j <4;j++) 
cout <<setw(3) <<a[i][j]; 
cout <<endl; 
} 
cout <<endl <<endl; 
for( i=0;i <4;i++) 
{ for( j=0;j <5;j++) 
cout <<setw(3) <<b[i][j]; 
cout <<endl; 
} 
for( i=0;i <3;i++) 
	for( j=0;j <5;j++) 
		for(int k=0;k <4;k++) 
			c[i][j]+=a[i][k]*b[k][j]; 
	
for( i=0;i <3;i++) 
{for(int j=0;j <5;j++) 
cout <<setw(5) <<c[i][j]; 
cout <<endl; 
} 
} 

[ryfdizuo]

  4  1  2  5
  5  2  1  3
  2  4  5  7


  5  4  3  2  1
  2  3  4  5  6
  1  2  4  5  7
  1  5  5  5  5
   29   48   49   48   49
   33   43   42   40   39
   30   65   77   84   96
请按任意键继续. . .

[fallening]

template < class T > class Matrix
{
private:
  int Row;
  int Column;
  T **Data;
public:
  ......
  Matrix & operator* (const Matrix & M);
  Matrix & operator* (const T M);
};

...

template < class T > Matrix < T > &Matrix < T >::operator* (const Matrix & M)
{
  if (Column != M.Row)
    {
      exit (EXIT_FAILURE);
    }

  Matrix < T > Result (Row, M.Column);

  for (int i = 0; i < Row; ++i)
    {
      for (int j = 0; j < M.Column; ++j)
	{
	  for (int k = 0; k < Column; ++k)
	    {
	      Result.Data[i][j] += Data[i][k] * M.Data[k][j];
	    }
	}
    }
  if (Row != Column)
    {

      for (int i = 0; i < Row; ++i)
	{
	  delete[]Data[i];
	}
      delete[]Data;
    }

  Column = Result.Column;
  Data = new T *[Row];
  for (int i = 0; i < Row; ++i)
    {
      Data[i] = new T[Column];
      for (int j = 0; j < Column; ++j)
	{
	  Data[i][j] = Result[i][j];
	}
    }
  return *this;
}

template < class T > Matrix < T > &Matrix < T >::operator* (const T M)
{
  for (int i = 0; i < Row; ++i)
    {
      for (int j = 0; j < Column; ++j)
	{
	  Data[i][j] *= M;
	}
    }

  return *this;
}