在C ++中访问多维数组的整行 [英] Accessing an entire row of a multidimensional array in C++

问题描述

一个人如何访问多维数组的整个行? 例如:

How would one access an entire row of a multidimensional array? For example:

int logic[4][9] = {
    {0,1,8,8,8,8,8,1,1},
    {1,0,1,1,8,8,8,1,1},
    {8,1,0,1,8,8,8,8,1},
    {8,1,1,0,1,1,8,8,1}
};

// I want everything in row 2. So I try...
int temp[9] = logic[2];

我的尝试引发了错误:

数组初始化需要花括号

array initialization needs curly braces

我知道我可以使用FOR循环来检索行，但是我很好奇是否有更明显的解决方案.

I know I can retrieve the row using a FOR loop, however I'm curious if there was a more obvious solution.

推荐答案

这不是数组/指针在C ++中的工作方式.

That's not how arrays/pointers work in C++.

该数组存储在内存中的某个位置.为了引用相同的数据，您需要一个指向数组开头的指针:

That array is stored somewhere in memory. In order to reference the same data, you'll want a pointer that points to the the beginning of the array:

int* temp = logic[2];

或者，如果您需要该阵列的副本，则必须分配更多的空间.

Or if you need a copy of that array, you'll have to allocate more space.

通常:

int temp[9];
for (int i = 0; i < 9; i++) {
    temp[i] = logic[2][i];
}

动态地:

// allocate
int* temp = new int(9);
for (int i = 0; i < 9; i++) {
    temp[i] = logic[2][i];
}

// when you're done with it, deallocate
delete [] temp;

或者由于使用的是C ++，如果您不想担心所有这些内存和指针，那么对于动态大小的数组应使用std::vector<int>，对于静态大小的数组应使用std::array<int>.

Or since you're using C++, if you want to not worry about all this memory stuff and pointers, then you should use std::vector<int> for dynamically sized arrays and std::array<int> for statically sized arrays.

#include <array>
using namespace std;

array<array<int, 9>, 4> logic = {
  {0,1,8,8,8,8,8,1,1},
  {1,0,1,1,8,8,8,1,1},
  {8,1,0,1,8,8,8,8,1},
  {8,1,1,0,1,1,8,8,1}
}};

array<int, 9> temp = logic[2];

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