堆栈展开是在运行时从函数调用堆栈中删除函数项的过程。它通常与异常处理有关。在c++中，当发生异常时，函数调用堆栈会线性地搜索异常处理程序，在带有异常处理程序的函数之前的所有条目都将从函数调用堆栈中删除。

我不知道你是否读过这篇文章，但维基百科关于调用堆栈的文章有一个很好的解释。

解除:

Returning from the called function will pop the top frame off of the stack, perhaps leaving a return value. The more general act of popping one or more frames off the stack to resume execution elsewhere in the program is called stack unwinding and must be performed when non-local control structures are used, such as those used for exception handling. In this case, the stack frame of a function contains one or more entries specifying exception handlers. When an exception is thrown, the stack is unwound until a handler is found that is prepared to handle (catch) the type of the thrown exception. Some languages have other control structures that require general unwinding. Pascal allows a global goto statement to transfer control out of a nested function and into a previously invoked outer function. This operation requires the stack to be unwound, removing as many stack frames as necessary to restore the proper context to transfer control to the target statement within the enclosing outer function. Similarly, C has the setjmp and longjmp functions that act as non-local gotos. Common Lisp allows control of what happens when the stack is unwound by using the unwind-protect special operator. When applying a continuation, the stack is (logically) unwound and then rewound with the stack of the continuation. This is not the only way to implement continuations; for example, using multiple, explicit stacks, application of a continuation can simply activate its stack and wind a value to be passed. The Scheme programming language allows arbitrary thunks to be executed in specified points on "unwinding" or "rewinding" of the control stack when a continuation is invoked.

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堆栈展开主要是c++的概念，处理当堆栈分配的对象的作用域退出时(正常退出或通过异常退出)如何销毁。

假设你有这样一段代码:

void hw() {
    string hello("Hello, ");
    string world("world!\n");
    cout << hello << world;
} // at this point, "world" is destroyed, followed by "hello"

堆栈展开是在运行时从函数调用堆栈中删除函数项的过程。它通常与异常处理有关。在c++中，当发生异常时，函数调用堆栈会线性地搜索异常处理程序，在带有异常处理程序的函数之前的所有条目都将从函数调用堆栈中删除。

在Java堆栈中，不宽或不伤人不是很重要(使用垃圾收集器)。在许多异常处理论文中，我看到了这个概念(堆栈展开)，特别是那些作者在C或c++中处理异常处理。对于try catch块，我们不应该忘记:在局部块之后释放所有对象的堆栈。

在一般意义上，堆栈“unwind”几乎等同于函数调用的结束和随后的堆栈弹出。

然而，特别是在c++的情况下，堆栈展开必须与c++如何调用自任何代码块开始分配的对象的析构函数有关。在块中创建的对象将按照其分配的相反顺序被释放。