一个局部变量的C ++动态内存分配(C++ dynamic memory allocation of a local variable)

一个局部变量的C ++动态内存分配(C++ dynamic memory allocation of a local variable)

我在学校有一个计算机科学课，我们的老师正在讨论动态内存分配及其原因

cin>>size; int array[size]; // According to him this should result in a compiler error

这不应该工作，而是我们应该使用：

int *p, size; cin>>size; p = new int[size] ... delete[] p;

我的问题是，为什么第一个例子工作，如果你不能像这样动态地声明数组？

更新：所有测试都在GNU GCC Compliler中完成 ，上面的代码位于主函数内部

I had a computer science class at school and our teacher was talking about dynamic memory allocation and why

cin>>size; int array[size]; // According to him this should result in a compiler error

this shouldn't work and instead we were supposed to use:

int *p, size; cin>>size; p = new int[size] ... delete[] p;

My question is, why does the first example work if you cannot declare dynamically arrays like that?

UPDATE: All tests are made in GNU GCC Compliler and the code above is inside the main function

最满意答案

您正在使用支持可变长度数组的非标准编译器。 你的教授是对的， int array[size]不应该编译。

你的教授也是 错误 告诉你使用p = new int[size] 。 他应该做的是告诉你使用std::vector<int> p(size) 。 （好吧，出于教育目的，这没关系）:)

You're using a non-standard compiler, that supports variable length arrays. Your professor is right, int array[size] shouldn't compile.

Your professor is also wrong telling you to use p = new int[size]. What he should do is tell you to use std::vector<int> p(size). (okay, for educational purposes this is OK) :)