C = AB

• 函数传入二维数组列数一定要是const
• 最终C(i, j)每个位置上的结果是K次乘法相加的结果

#include <bits/stdc++.h>
using namespace std;
const int N = 2, K = 3, M = 4;


void mul(int c[][M], int a[][K], int b[][M]){
    int temp[N][M] = {0};
    for(int i = 0; i < N; i ++ )
        for(int j = 0; j < M; j ++ )
            for(int k = 0; k < K; k ++ )
                temp[i][j] += a[i][k] * b[k][j];
    memcpy(c, temp, sizeof temp);
}
int main(){
    int A[N][K] = {
        {1, 2, 3},
        {4, 5, 6}
    };
    int B[K][M] = {
        {1, 2, 3, 4},
        {4, 3, 2, 1},
        {5, 6, 7, 8}
    };
    int C[N][M];
    mul(C, A, B);

    cout << "C:" << endl;
    for(int i = 0; i < N; i ++ ){
        for(int j = 0; j < M; j ++ ){
            printf("%d ", C[i][j]);
        }
        puts("");
    }



    return 0;
}