C 程序：通过将矩阵传递给函数将两个矩阵相乘

原文： https://www.programiz.com/cpp-programming/examples/matrix-multiplication-function

在此示例中，您将学习将两个矩阵相乘并使用用户定义的函数进行显示。

要理解此示例，您应该了解以下 C++ 编程主题：

• C++ 数组
• C++ 多维数组
• 在 C++ 编程中将数组传递给函数

该程序要求用户输入矩阵的大小（行和列）。

然后，它要求用户输入两个矩阵的元素，最后将两个矩阵相乘并显示结果。

要执行此任务，需要执行三个步骤：

1. 从用户那里获取矩阵元素
2. 乘以两个矩阵
3. 在乘法后显示结果矩阵

示例：通过将矩阵传递给函数来相乘

#include <iostream>
using namespace std;
void enterData(int firstMatrix[][10], int secondMatrix[][10], int rowFirst, int columnFirst, int rowSecond, int columnSecond);
void multiplyMatrices(int firstMatrix[][10], int secondMatrix[][10], int multResult[][10], int rowFirst, int columnFirst, int rowSecond, int columnSecond);
void display(int mult[][10], int rowFirst, int columnSecond);
int main()
{
    int firstMatrix[10][10], secondMatrix[10][10], mult[10][10], rowFirst, columnFirst, rowSecond, columnSecond, i, j, k;
    cout << "Enter rows and column for first matrix: ";
    cin >> rowFirst >> columnFirst;
    cout << "Enter rows and column for second matrix: ";
    cin >> rowSecond >> columnSecond;
    // If colum of first matrix in not equal to row of second matrix, asking user to enter the size of matrix again.
    while (columnFirst != rowSecond)
    {
        cout << "Error! column of first matrix not equal to row of second." << endl;
        cout << "Enter rows and column for first matrix: ";
        cin >> rowFirst >> columnFirst;
        cout << "Enter rows and column for second matrix: ";
        cin >> rowSecond >> columnSecond;
    }
    // Function to take matrices data
        enterData(firstMatrix, secondMatrix, rowFirst, columnFirst, rowSecond, columnSecond);
        // Function to multiply two matrices.
        multiplyMatrices(firstMatrix, secondMatrix, mult, rowFirst, columnFirst, rowSecond, columnSecond);
        // Function to display resultant matrix after multiplication.
        display(mult, rowFirst, columnSecond);
    return 0;
}
void enterData(int firstMatrix[][10], int secondMatrix[][10], int rowFirst, int columnFirst, int rowSecond, int columnSecond)
{
    int i, j;
    cout << endl << "Enter elements of matrix 1:" << endl;
    for(i = 0; i < rowFirst; ++i)
    {
        for(j = 0; j < columnFirst; ++j)
        {
            cout << "Enter elements a"<< i + 1 << j + 1 << ": ";
            cin >> firstMatrix[i][j];
        }
    }
    cout << endl << "Enter elements of matrix 2:" << endl;
    for(i = 0; i < rowSecond; ++i)
    {
        for(j = 0; j < columnSecond; ++j)
        {
            cout << "Enter elements b" << i + 1 << j + 1 << ": ";
            cin >> secondMatrix[i][j];
        }
    }
}
void multiplyMatrices(int firstMatrix[][10], int secondMatrix[][10], int mult[][10], int rowFirst, int columnFirst, int rowSecond, int columnSecond)
{
    int i, j, k;
    // Initializing elements of matrix mult to 0.
    for(i = 0; i < rowFirst; ++i)
    {
        for(j = 0; j < columnSecond; ++j)
        {
            mult[i][j] = 0;
        }
    }
    // Multiplying matrix firstMatrix and secondMatrix and storing in array mult.
    for(i = 0; i < rowFirst; ++i)
    {
        for(j = 0; j < columnSecond; ++j)
        {
            for(k=0; k<columnFirst; ++k)
            {
                mult[i][j] += firstMatrix[i][k] * secondMatrix[k][j];
            }
        }
    }
}
void display(int mult[][10], int rowFirst, int columnSecond)
{
    int i, j;
    cout << "Output Matrix:" << endl;
    for(i = 0; i < rowFirst; ++i)
    {
        for(j = 0; j < columnSecond; ++j)
        {
            cout << mult[i][j] << " ";
            if(j == columnSecond - 1)
                cout << endl << endl;
        }
    }
}

输出

Enter rows and column for first matrix: 3
2
Enter rows and column for second matrix: 3
2
Error! column of first matrix not equal to row of second.
Enter rows and column for first matrix: 2
3
Enter rows and column for second matrix: 3
2
Enter elements of matrix 1:
Enter elements a11: 3
Enter elements a12: -2
Enter elements a13: 5
Enter elements a21: 3
Enter elements a22: 0
Enter elements a23: 4
Enter elements of matrix 2:
Enter elements b11: 2
Enter elements b12: 3
Enter elements b21: -9
Enter elements b22: 0
Enter elements b31: 0
Enter elements b32: 4
Output Matrix:
24 29
6  25