什么是C＃无效**？ [英] What is void** in C#?

问题描述

我期待通过C＃程序，它使用C语言编写的一个图书馆，我碰到这条线，并不能肯定这是什么来源：

I'm looking through the source of a C# program that uses a library written in C. I came across this line and was unsure what it was:

cvbimUNSAFE.GetImageVPA ((cvbim.IMG)cvImg.Image, 0, (void**)&lpImageBits, &pVPAT);

是什么类型的对象无效** ？我做了一些谷歌搜索，只能找到关于无效* ，这是一个指向某种渔获所有顶级类型的信息，如果我理解正确的。

What is an object of type void **? I did some Google searches and could only find information about void*, which is a pointer to a sort of catch all top level type, if I understood correctly.

推荐答案

这是一个指针的指针的东西没有规定。基本上，只要把它看作一个内存指针到原始内存指针。

It's a pointer to a pointer to something not specified. Basically, just think of it as a memory pointer to a raw memory pointer.

因此​​， INT ** 是一个指向一个指向 INT ，但无效** 是一个指针的指针，但它没有指定什么指针指向。

So, int** is a pointer to a pointer to an int, but void** is a pointer to a pointer, but it's not specified what that pointer is pointing at.

我做了一些谷歌搜索，只能找到有关的void *，这是一个指向某种渔获所有顶级类型的信息，如果我理解正确的。

I did some google searches and could only find information about void*, which is a pointer to a sort of catch all top level type, if I understood correctly.

不太。 无效* 是一个指针的东西，只是没有规定它是什么东西，应该只是被看作是一个指向内存的原料大块，你需要用些结构。例如，的malloc 返回无效* ，因为它返回一个指向内存的原料大块。

Not quite. void* is a pointer to something, it's just not specified what that something is and should just be thought of as a pointer to a raw hunk of memory that you have to apply some structure to. For example, malloc returns a void* because it's returning a pointer to a raw hunk of memory.

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