C ++表达式必须具有恒定值 [英] c++ expression must have a constant value

问题描述

我有这种方法:

void createSomething(Items &items)
{
    int arr[items.count]; // number of items
}

但是它抛出一个错误:

expression must have a constant value

我发现了以下解决方案:

I found just this solution:

int** arr= new int*[items.count];

所以我问有一种更好的方法来处理这个问题吗?

so I'm asking is there a better way how do handle this?

推荐答案

您可以使用 std :: vector

void createSomething(Items &items)
{
    std::vector<int> arr(items.count); // number of items
}

第一种方法行不通的原因是必须在编译时知道数组的大小(

The reason your first method won't work is that the size of an array must be know at compile time (without using compiler extensions), so you have to use dynamically sized arrays. You can use new to allocate the array yourself

void createSomething(Items &items)
{
    int* arr = new int[items.count]; // number of items

    // also remember to clean up your memory
    delete[] arr;
}

但是使用 std :: vector 更加安全，恕我直言.

But it is safer and IMHO more helpful to use a std::vector.

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