堆栈溢出 - 静态内存与动态内存 [英] Stack overflow - static memory vs. dynamic memory

问题描述

如果在C / C ++的main函数中写入 int m [1000000]; ，它将得到堆栈溢出的运行时错误。相反，如果你写 vector< int> m; 然后push_back 1000000元素，它会运行正常。

If you write int m[1000000]; inside the main function of C/C++, it will get a runtime error for stack overflow. Instead if you write vector<int> m; and then push_back 1000000 elements there, it will run fine.

我很好奇为什么会发生这种情况。他们都是本地内存，不是吗？提前致谢。

I am very curious about why this is happening. They both are local memory, aren't they? Thanks in advance.

推荐答案

是的，向量本身是一个自动（堆栈）对象。但是该向量包含一个指向其内容的指针（内部动态数组），并且将在堆上分配（默认情况下）。为了简化一点，你可以认为向量是做 malloc / realloc 或 new [] 内部调用（实际上它使用 allocator ）。

Yes, the vector itself is an automatic (stack) object. But the vector holds a pointer to its contents (an internal dynamic array), and that will be allocated on the heap (by default). To simplify a little, you can think of vector as doing malloc/realloc or new[] calls internally (actually it uses an allocator).

编辑：我注意到，自动变量分配在堆栈上，而 malloc 一般在堆上分配。每个可用的内存是平台甚至配置特定的，但是可用的堆栈内存通常更受限制。

As I noted, automatic variables are allocated on the stack, while malloc generally allocates on the heap. The available memory for each are platform and even configuration-specific, but the available stack memory is typically much more limited.

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