std :: list c的数组 [英] array of std::list c

问题描述

我找不到对此的任何人工解释: 我如何创建像这样的列表数组

I can't find any human explaination for this: how can I create an array of lists like

std::list<int> mylist[size] ?

如果我将其放在程序中，它会编译但会产生一些问题，因为它不执行任何代码(如果我写出不带[size]的mylist，其余代码也可以正常工作)

If I put this in my program it compiles but creates some problems since it doesn't execute any code (the rest of the code works just fine if I write mylist w/out [size])

我在某处读到，不建议使用C的原始数组. 有哪些替代方案?

I was reading somewhere that using primitive arrays of C is not recommended; what are the alternatives?

对不起，谢谢

推荐答案

您的声明不正确，并且在C ++中不受支持.您试图在运行时声明一个可变大小的数组，这是C99的功能，但不是C ++中的功能.参见此处:运行时的数组大小无动态可以分配吗?

Your declaration is incorrect, and not supported in C++. You're trying to declare a variable-sized array at run-time, which IS a C99 feature, but is not in C++. See here: Array size at run time without dynamic allocation is allowed?

您有这个:

std::list<int> mylist[size]

这是您需要的:

std::list<int> mylist[] = new std::list<int>[size];

但这仍然不是一个好主意，因为您稍后需要使用delete []对其进行取消分配.正如其他人所说的，您可以通过几种不同的方式来做到这一点，所有这些方式对于c ++都是更好的:

But this is still a bad idea, as you need to de-allocate it later with delete []. As others have said, you can do it a couple of different ways, all of which are better for c++:

std::list< std::list< int > > myListOfLists;      // Linked list of linked lists
std::vector< std::list< int > > myVectorOfLists;  // Better, a vector is more like an array
std::array<std::list<int>, 10> this_would_do;     // From above, only works if you know the array size at compile-time

希望这对您有所帮助.

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