# C++ 程序：使用多維數組將兩個矩陣相乘 > 原文： [https://www.programiz.com/cpp-programming/examples/matrix-multiplication](https://www.programiz.com/cpp-programming/examples/matrix-multiplication) #### 該程序分別采用兩個階為`r1 * c1`和`r2 * c2`的矩陣。 然后，程序將這兩個矩陣相乘（如果可能），并將其顯示在屏幕上。 要理解此示例，您應該了解以下 [C++ 編程](/cpp-programming "C++ tutorial")主題： * [C++ 多維數組](/cpp-programming/multidimensional-arrays) * [C++ 數組](/cpp-programming/arrays) * * * 若要將兩個矩陣相乘，第一個矩陣的列數應等于第二個矩陣的行數。 該程序顯示錯誤，直到第一矩陣的列數等于第二矩陣的行數。 ## 示例：不使用函數將兩個矩陣相乘 ```cpp #include <iostream> using namespace std; int main() { int a[10][10], b[10][10], mult[10][10], r1, c1, r2, c2, i, j, k; cout << "Enter rows and columns for first matrix: "; cin >> r1 >> c1; cout << "Enter rows and columns for second matrix: "; cin >> r2 >> c2; // If column of first matrix in not equal to row of second matrix, // ask the user to enter the size of matrix again. while (c1!=r2) { cout << "Error! column of first matrix not equal to row of second."; cout << "Enter rows and columns for first matrix: "; cin >> r1 >> c1; cout << "Enter rows and columns for second matrix: "; cin >> r2 >> c2; } // Storing elements of first matrix. cout << endl << "Enter elements of matrix 1:" << endl; for(i = 0; i < r1; ++i) for(j = 0; j < c1; ++j) { cout << "Enter element a" << i + 1 << j + 1 << " : "; cin >> a[i][j]; } // Storing elements of second matrix. cout << endl << "Enter elements of matrix 2:" << endl; for(i = 0; i < r2; ++i) for(j = 0; j < c2; ++j) { cout << "Enter element b" << i + 1 << j + 1 << " : "; cin >> b[i][j]; } // Initializing elements of matrix mult to 0. for(i = 0; i < r1; ++i) for(j = 0; j < c2; ++j) { mult[i][j]=0; } // Multiplying matrix a and b and storing in array mult. for(i = 0; i < r1; ++i) for(j = 0; j < c2; ++j) for(k = 0; k < c1; ++k) { mult[i][j] += a[i][k] * b[k][j]; } // Displaying the multiplication of two matrix. cout << endl << "Output Matrix: " << endl; for(i = 0; i < r1; ++i) for(j = 0; j < c2; ++j) { cout << " " << mult[i][j]; if(j == c2-1) cout << endl; } return 0; } ``` **輸出** ```cpp 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 ``` 在該程序中，首先要求用戶輸入兩個矩陣的大小。 為了乘法，第一矩陣的列應等于第二矩陣的行。 如果不滿足此條件，則使用`while`循環再次詢問矩陣的大小。 然后，要求用戶輸入兩個矩陣，最后計算并顯示兩個矩陣的輸出。 由于該程序冗長且難以調試，因此最好通過將其傳遞給函數來解決該程序。 訪問此頁面以了解通過將數組傳遞給函數來乘以[矩陣的信息](/cpp-programming/examples/matrix-multiplication-function)。