C++ 数组 - 表达式必须有一个常量值 [英] c++ array - expression must have a constant value

问题描述

当我尝试从我声明的变量创建数组时出现错误.

I get an error when I try to create an array from the variables I declared.

int row = 8;
int col= 8;
int [row][col];

为什么我会收到此错误:

Why do I get this error:

表达式必须有一个常量值.

expression must have a constant value.

推荐答案

当创建这样的数组时，它的大小必须是恒定的.如果你想要一个动态大小的数组，你需要在堆上为它分配内存，你还需要在完成后使用 delete 释放它:

When creating an array like that, its size must be constant. If you want a dynamically sized array, you need to allocate memory for it on the heap and you'll also need to free it with delete when you're done:

//allocate the array
int** arr = new int*[row];
for(int i = 0; i < row; i++)
    arr[i] = new int[col];

// use the array

//deallocate the array
for(int i = 0; i < row; i++)
    delete[] arr[i];
delete[] arr;

如果你想要一个固定的大小，那么它们必须被声明为 const:

If you want a fixed size, then they must be declared const:

const int row = 8;
const int col = 8;
int arr[row][col];

还有，

int [row][col];

甚至不提供变量名.

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