数组与矩阵(1)_矩阵相乘

矩阵相乘是矩阵运算中十分基本的概念。

在这里我用类的形式封装了矩阵的存储和表示。内部存储的方式是采用一维数组的形式。

另外引入了异常处理的机制。也算是对C++的基本概念进行了实际应用了。


//error class


class BadOccur




...{


public:


BadOccur(int nErrorNum)




...{


ErrorNum = nErrorNum;


}


void BadOccurPrint()




...{


cout << ErrorNum << " error occurs!" << endl;


}


private:


int ErrorNum;


};




//matrix class


class CMatrix




...{


public:


CMatrix(int Row = 0, int Col = 0)




...{


if ( Row < 0 || Col < 0)




...{


throw BadOccur(2);


}


else




...{


nRows = Row;


nCols = Col;


pValueArray = new int [Row * Col];


}


}


int operator()(int Row, int Col) const //get the element from the position you have given




...{


if ( Row < 1 || Row > nRows || Col < 1 || Col > nCols)




...{


throw BadOccur(1);//cause error 1


}


return pValueArray[(Row - 1) * nCols + Col - 1];


}


int& SetData(int i, int j)//abstract the position for you to set data




...{


return pValueArray[(i - 1)* nCols + j - 1];


}


int nRows;


int nCols;


int* pValueArray;


};






/**//*


* Function Name ：MultiplyMatrix


* function ：multiply two matrices


* detail ：none


* author ：weixiong


* time ：2007-2-1


* return type ：bool


* return description : true two matrices has multiplied


* false two matrices can't be multiplied


* function parameters ：CMatrix& MatrixA multiply matrix A and B


* CMatrix& MatrixB


*


*/


bool MultiplyMatrix(CMatrix& MatrixA, CMatrix& MatrixB, CMatrix& ResultMatrix)




...{


if (MatrixA.nCols != MatrixB.nRows)




...{


return false;


}


else




...{


int Sum = 0;


for (int Row = 1; Row <= MatrixA.nRows; Row++)




...{


for (int Col = 1; Col <= MatrixB.nCols; Col++)




...{


for (int i = 1; i <= MatrixA.nCols; i++)




...{


Sum = Sum + MatrixA(Row, i) * MatrixB(i, Col);


}


ResultMatrix.pValueArray[(Row - 1) * MatrixB.nCols + Col - 1] = Sum;


}


}


return true;


}


}


int main()




...{


try




...{


//CMatrix ErrorMatrix(-1, 0);//example of cause error 2


int Row1 = 0;


int Col1 = 0;


cout << "Please enter the row and col for the first matrix." << endl;


cin >> Row1 >> Col1;


int Num = 1;


CMatrix MatrixA(Row1, Col1);


for (int i = 1; i <= Row1; i++)




...{


for (int j = 1; j <= Col1; j++)




...{


MatrixA.SetData(i, j) = Num++;


}


}


//int a = MatrixA(0, 2);//example of cause error 1


int Row2 = 0;


int Col2 = 0;


cout << "Please enter the row and col for the second matrix." << endl;


cin >> Row2 >> Col2;


Num = 1;


CMatrix MatrixB(Row2, Col2);


for (int i = 1; i <= Row2; i++)




...{


for (int j = 1; j <= Col2; j++)




...{


MatrixB.SetData(i, j) = Num++;


}


}


CMatrix ResultMatrix(Row1, Col2);


MultiplyMatrix(MatrixA, MatrixB, ResultMatrix);


getchar();


}


catch(BadOccur m)




...{


m.BadOccurPrint();


}


}