【C++练习题】求任意行列的两个矩阵的乘积（普通函数实现+类实现）

小咪咪 2021-06-11 15:13 338阅读 0赞

## 一、题目 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_20_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWl5aXhpbg_size_32_color_3FF7F1_t_70][]

学弟问了一道题，想想好久没有写C++的题了，想着练练手，也把这道题分享给大家。

我们知道用matlab实现这个代码是很容易的，毕竟玩矩阵，matlab是专业的，C++就不一样了，考虑的问题有好多，实现方法也有很多，我就把自己写的分享给大家。

我们用一个两行两列的矩阵A和两行三列的矩阵B做测试：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWl5aXhpbg_size_26_color_F42FFF_t_50][]

## 二、普通函数实现 ##

### 1、代码 ###

#include<iostream>
    using namespace std;
    
    int rowsA;
    int colsA;
    int rowsB;
    int colsB;
    int ** matrixA = new int *[rowsA];
    int ** matrixB = new int *[rowsB];
    int ** matrixAB = new int *[rowsA];
    
    void ProductOfMatrix(int ** matrixA, int ** matrixB) {
    	for (int i = 0; i < rowsA; i++)
    	{
    		matrixAB[i] = new int[colsB];
    		for (int j = 0; j < colsB; j++)
    		{
    			matrixAB[i][j] = 0;
    			for (int m = 0; m < colsA; m++)
    			{
    				matrixAB[i][j] += matrixA[i][m] * matrixB[m][j];
    			}
    		}
    	}
    }
    
    void OutputMatrix(int ** matrix,int rows,int cols) {
    	for (int i = 0; i < rows; i++)
    	{
    		for (int j = 0; j < cols; j++)
    			cout << matrix[i][j] << "\t";
    		cout << endl;
    	}
    	cout << endl;
    }
    
    void main() {
    	cout << "输入矩阵A的行：";
    	cin >> rowsA;
    	cout << "输入矩阵A的列：";
    	cin >> colsA;
    	rowsB = colsA;
    	cout << "输入矩阵B的列：";
    	cin >> colsB;
    
    	for (int i = 0; i < rowsA; i++)
    	{
    		matrixA[i] = new int[colsA];
    		cout << "\n输入矩阵A的第"<<i+1<<"行数据(该行共有" << colsA << "个数据) : \n";
    		for (int j = 0; j < colsA; j++)
    		{
    			cin >> matrixA[i][j];
    		}
    	}
    
    	for (int i = 0; i < rowsB; i++)
    	{
    		matrixB[i] = new int[colsB];
    		cout << "\n输入矩阵B的第"<<i+1<<"行数据(该行共有" << colsB << "个数据) : \n";
    		for (int j = 0; j < colsB; j++)
    		{
    			cin >> matrixB[i][j];
    		}
    	}
    
    	ProductOfMatrix(matrixA, matrixB);
    	cout << "【矩阵A】\n";
    	OutputMatrix(matrixA, rowsA, colsA);
    	cout << "【矩阵B】\n";
    	OutputMatrix(matrixB, rowsB, colsB);
    	cout << "【A × B】\n";
    	OutputMatrix(matrixAB, rowsA, colsB);
    }

### 2、运行结果 ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWl5aXhpbg_size_24_color_FFF03F_t_70][]

## 三、类实现 ##

### 1、代码 ###

#include<iostream>
    using namespace std;
    
    class Matrix
    {
    public:
    	Matrix(int rows,int cols);
    	~Matrix();
    	void ProductOfMatrix(Matrix MA, Matrix MB);
    	void Assignment();
    	void OutputMatrix();
    private:
    	int rows;
    	int cols;
    	int **data;
    };
    
    Matrix::Matrix(int rows, int cols)
    {
    	this->rows = rows;
    	this->cols = cols;
    	this->data = new int *[rows];
    	for (int i = 0; i < rows; i++)
    	{
    		this->data[i] = new int[cols];
    	}
    }
    
    Matrix::~Matrix()
    {
    }
    
    void Matrix::Assignment() {
    	for (int i = 0; i < this->rows; i++)
    	{
    		cout << "\n输入矩阵的第" << i + 1 << "行数据(该行共有" << this->cols << "个数据) : \n";
    		for (int j = 0; j < this->cols; j++)
    		{
    			cin >> this->data[i][j];
    		}
    	}
    }
    
    void Matrix::ProductOfMatrix(Matrix MA, Matrix MB) {
    	for (int i = 0; i < MA.rows; i++)
    	{
    		for (int j = 0; j < MB.cols; j++)
    		{
    			this->data[i][j] = 0;
    			for (int m = 0; m < MA.cols; m++)
    			{
    				this->data[i][j] += MA.data[i][m] * MB.data[m][j];
    			}
    		}
    	}
    }
    
    void Matrix::OutputMatrix() {
    	for (int i = 0; i < this->rows; i++)
    	{
    		for (int j = 0; j < this->cols; j++)
    			cout << this->data[i][j] << "\t";
    		cout << endl;
    	}
    	cout << endl;
    }
    
    void main() {
    	int rowsA;
    	int colsA;
    	int rowsB;
    	int colsB;
    	cout << "输入矩阵A的行：";
    	cin >> rowsA;
    	cout << "输入矩阵A的列：";
    	cin >> colsA;
    	rowsB = colsA;
    	cout << "输入矩阵B的列：";
    	cin >> colsB;
    	Matrix MA(rowsA, colsA);
    	Matrix MB(rowsB, colsB);
    	Matrix MAB(rowsA, colsB);
    	cout << "\n【矩阵A赋值】";
    	MA.Assignment();
    	cout << "\n【矩阵B赋值】";
    	MB.Assignment();
    	MAB.ProductOfMatrix(MA, MB);
    	cout << "\n【矩阵A】\n";
    	MA.OutputMatrix();
    	cout << "\n【矩阵B】\n";
    	MB.OutputMatrix();
    	cout << "\n【A × B】\n";
    	MAB.OutputMatrix();
    }

### 2、运行结果 ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWl5aXhpbg_size_24_color_F1F41F_t_70][]

大家还可以使用结构体，还可以加上数据结构中的矩阵，总之方法很多，希望大家能多多思考。

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWl5aXhpbg_size_26_color_F42FFF_t_50]: /images/20210516/17e50a7795514eefb004c0c213a51771.png
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