什么是铸造一个空指针的原因是什么？ [英] What are the reasons for casting a void pointer?

问题描述

我学习从头C ++，因此我没有C的专家了解在C ++中，你不能一个空指针转换为任何别的东西，我明白背后的原因。但是，我知道，在C，就可以了。什么是这种情况的可能原因？这似乎只是它是类型安全一个巨大的窟窿，这（对我来说）似乎是一件坏事。

I'm learning C++ from scratch, and as such I don't have an expert understanding of C. In C++, you can't cast a void pointer to whatever, and I understand the reasons behind that. However, I know that in C, you can. What are the possible reasons for this? It just seems like it's be a huge hole in type safety, which (to me) seems like a bad thing.

推荐答案

您可以施放一个无效* 中的两个的语言另一个指针。也许你含蓄的意思。

You can cast a void* to another pointer in both languages. Perhaps you meant implicitly.

这是非常方便的在C不必是明确了。在C ++中，我们有模板，所以编写普通code没有必要为无效* 铸造和诸如此类的东西。在C语言中没有选择的余地。一个普通的容器必须持有无效* 的对象，而且它更容易反复说 MYDATA * D =节点; 那么它是 MYDATA * D =（MYDATA *）节点。

It's very convenient in C to not have to be explicit about it. In C++ we have templates, so to write generic code there's no need for void* casting and whatnot. In C there is no choice. A generic container has to hold void* to objects, and it's much easier to repeatedly say mydata* d = node; then it is mydata* d = (mydata*)node;.

所以这是pretty就像你说的。在C型一般安全性在C确实没有得到一样的重视++，特别是当它来到无效* ，因为它被假设是一个简单的通用指针随你。有没有必要在C ++中，所以最好还是让它当你处理它明确。

So it's pretty much like you said. In C type safety in general didn't receive as much emphasis as it did in C++, especially when it came to void* because it was suppose to be a simple generic pointer to whatever. There's no need for that in C++, so better make it explicit when you're dealing with it.

这篇关于什么是铸造一个空指针的原因是什么？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！