在C ++中返回二维数组对角元素之和的函数[重复]

Question

我需要创建一个函数来计算矩阵对角线上元素的总和，签名为int diagonal(int array[4][4])

这是我尝试过的：

int diagonal(int array[4][4]){
    int sum = 0;

    for (int i = 0; i < 4; i++){
        for (int j = 0 ; j < 4; j++){
            if (i == j){
            sum = sum + array[i,j];
            }
        }
    }
return sum;
}



#include <iostream>

extern int diagonal(int[][]);
int main (){
    int array[4][4] = {{1,2,3,4},{1,2,3,4},{1,2,3,4},{1,2,3,4}};
    std::cout << "The sum is: " << diagonal(array) << std::endl;    
    return 0;
}

但它会产生一些错误消息，我似乎不明白为什么会这样：

main-1-1.cpp:3:27: error: multidimensional array must have bounds for all dimensions except the first
 extern int diagonal(int[][]);
                           ^
main-1-1.cpp: In function ‘int main()’:
main-1-1.cpp:6:47: error: too many arguments to function ‘int diagonal()’
  std::cout << "The sum is: " << diagonal(array) << std::endl; 
                                               ^
main-1-1.cpp:3:12: note: declared here
 extern int diagonal(int[][]);
            ^
function-1-1.cpp: In function ‘int diagonal(int (*)[4])’:
function-1-1.cpp:8:14: error: invalid conversion from ‘int*’ to ‘int’ [-fpermissive]
    sum = sum + array[i,j];

有人可以向我解释一下吗？

Answer 1

int diagonal(int array[][4]){
    int sum = 0;

    for (int i = 0; i < 4; i++){
        for (int j = 0 ; j < 4; j++){
            if (i == j){
            sum = sum + array[i][j];
            }
        }
    }
return sum;
}



#include <iostream>

extern int diagonal(int[][4]);
int main (){
    int array[4][4] = {{1,2,3,4},{1,2,3,4},{1,2,3,4},{1,2,3,4}};
    std::cout << "The sum is: " << diagonal(array) << std::endl;    
    return 0;
}

您可以在第一个 [ ] 中输入任何数字，但编译器会忽略它。将向量作为参数传递时，您必须指定除第一个维度之外的所有维度。 简而言之，您不需要在函数声明中为第一个 [ ]

传递值

Answer 2

这个问题的答案在这里Passing a 2D array to a C++ function

尝试这种方式，它会更简单一些

#include <iostream>
int diagonal(int array[][4])
{
    int sum = 0;
    for(int I = 0; I < 4; I++)
    {
        sum += array[I][I];
    }
    return sum;
}

int main()
{
    int array[4][4] = {{1,2,3,4}, {1,2,3,4}, {1,2,3,4}, {1,2,3,4}};
    std::cout << "sum is " << diagonal(array) << std::endl;
    return 0;
}