C ++返回但未存储的值会发生什么? [英] C++ what happens to a value that is returned but is not stored?

问题描述

假设我有一个返回 int 的函数.我不存储函数调用的值.我认为它没有存储在内存中并消失在以太中，但我不知道.谢谢.

Say I have a function that returns an int. I don't store the value from the function call. I presume that it is not stored in memory and fades into the aether, but I don't know. Thank you.

推荐答案

int 返回值通常存储在寄存器中(例如，32 位或 64 位 Intel 上的 EAX 或 RAX，分别).

An int return value will normally be stored in a register (e.g., EAX or RAX on 32-bit or 64-bit Intel, respectively).

它不会褪色.当编译器出于其他目的需要该寄存器时，它只会被覆盖.如果有问题的函数是内联扩展的，编译器可能会检测到该值没有被使用，并省略编写或计算该值的代码.

It won't fade. It'll simply be overwritten when the compiler needs that register for some other purpose. If the function in question is expanded inline, the compiler may detect that the value isn't used, and elide the code to write or compute the value at all.

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