获取C ++函数的大小 [英] Getting The Size of a C++ Function

问题描述

我在阅读这个问题，因为我在一个C ++程序中试图找到一个函数的大小，它暗示可能有一种平台特定的方式。我的目标平台是windows

I was reading this question because I'm trying to find the size of a function in a C++ program, It is hinted at that there may be a way that is platform specific. My targeted platform is windows

我现在的方法如下：

1.获取一个指向函数的指针

2.增加指针（&计数器），直到我达到 ret

的机器代码值3.计数器将是函数的大小？

The method I currently have in my head is the following:
1. Obtain a pointer to the function
2. Increment the Pointer (& counter) until I reach the machine code value for ret
3. The counter will be the size of the function?

Edit1：为了澄清'size'的含义，我的意思是组成函数的字节数（机器码）。< br>
Edit2：有几个意见询问我为什么或我打算怎么做。诚实的答案是我没有意图，我不能真正看到知道一个函数长度的预编译时间的好处。 （虽然我敢肯定有一些）

To clarify what I mean by 'size' I mean the number of bytes (machine code) that make up the function.
There have been a few comments asking why or what do I plan to do with this. The honest answer is I have no intention, and I can't really see the benefits of knowing a functions length pre-compile time. (although I'm sure there are some)

这似乎是一个有效的方法给我，这将工作吗？

This seems like a valid method to me, will this work?

推荐答案

不，这不会工作：

1. 包含单个 ret 指令。


2. 即使它只包含一个 ret ，您不能只看单个字节 - 因为相应的值可能只是一个值，而不是一条指令。

1. There is no guarantee that your function only contains a single ret instruction.
2. Even if it only does contain a single ret, you can't just look at the individual bytes - because the corresponding value could appear as simply a value, rather than an instruction.

如果你限制你的编码风格，例如在你的函数中只有一个返回点，第一个问题可能可以解决，但是另一个基本上需要一个反汇编器，所以你可以分开单独的指令。

The first problem can possibly be worked around if you restrict your coding style to, say, only have a single point of return in your function, but the other basically requires a disassembler so you can tell the individual instructions apart.

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