输入两个m行n列的矩阵A和B,输出它们的和A+B

好的，下面是 C++ 代码实现：

#include <iostream>
using namespace std;

const int MAXN = 1005; // 矩阵最大行列数

int A[MAXN][MAXN], B[MAXN][MAXN], C[MAXN][MAXN]; // 定义三个矩阵

int main()
{
    int m, n;
    cout << "请输入矩阵的行数和列数：";
    cin >> m >> n;

    // 输入矩阵 A
    cout << "请输入矩阵 A：" << endl;
    for (int i = 0; i < m; i++)
        for (int j = 0; j < n; j++)
            cin >> A[i][j];

    // 输入矩阵 B
    cout << "请输入矩阵 B：" << endl;
    for (int i = 0; i < m; i++)
        for (int j = 0; j < n; j++)
            cin >> B[i][j];

    // 计算矩阵 C = A + B
    for (int i = 0; i < m; i++)
        for (int j = 0; j < n; j++)
            C[i][j] = A[i][j] + B[i][j];

    // 输出矩阵 C
    cout << "矩阵 A + B = " << endl;
    for (int i = 0; i < m; i++) {
        for (int j = 0; j < n; j++)
            cout << C[i][j] << " ";
        cout << endl;
    }

    return 0;
}

希望能帮助到你！