新的堆栈而不是堆（如alloca vs malloc） [英] new on stack instead of heap (like alloca vs malloc)

问题描述

有没有办法使用 new 关键字在堆栈上分配（ala alloca ）而不是堆>

解决方案

要在堆栈上分配，可以通过值声明您的对象为局部变量使用alloca获取一个指针，然后使用in-place new操作符：

  void * p = alloca（sizeof（Whatever） ）; 
 new（p）Whatever（constructorArguments）;但是，使用alloca和in-place new可以确保内存在返回时被释放，你可以使用alloca和in-place new。 up自动析构函数调用。如果你只是试图确保内存在退出范围后释放，请考虑使用 std :: auto_ptr< T> 或一些其他智能指针类型。 p> 
Is there a way to use the new keyword to allocate on the stack (ala alloca) instead of heap (malloc) ?

I know I could hack up my own but I'd rather not.
解决方案
To allocate on the stack, either declare your object as a local variable by value, or you can actually use alloca to obtain a pointer and then use the in-place new operator:
void *p = alloca(sizeof(Whatever));
new (p) Whatever(constructorArguments);
However, while using alloca and in-place new ensures that the memory is freed on return, you give up automatic destructor calling.  If you're just trying to ensure that the memory is freed upon exit from the scope, consider using std::auto_ptr<T> or some other smart pointer type.

                        
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