为什么我不应该编译C code与C ++或写C ++ code为在C编译？ [英] Why shouldn't I compile C code with a C++, or write C++ code to be compilable in C?

问题描述

我有写作code的习惯是在C和C ++编译器编译，例如：

I have a habit of writing code to be compilable on both C and C++ compilers, for example:

some_type *foo = (some_type *) malloc(sizeof (some_type));

当我问我的C code的问题，有人告诉我不要投malloc的。这是在有保证的C ++编译C分配内存的唯一途径。为什么这是一个在C坏主意？为什么这是一个在C坏主意++？

When I ask questions about my C code, I'm told not to cast malloc. This is the only way to allocate memory in C that's guaranteed to compile in C++. Why is this a bad idea in C? Why is this a bad idea in C++?

的C其他功能我会通过限制自己的那些对C ++的兼容功能的一个子集上缺少哪一个呢？为什么限制自己的同时也是兼容C的特征的一个子集C ++中的坏主意？

Which other features of C am I missing out on by restricting myself to a subset of features that are compatible to C++? Why is restricting myself to a subset of features that are also compatible to C++ a bad idea in C?

的C哪些功能++我会通过限制自己的是到C兼容功能的一个子集，错过了？为什么限制自己的同时也是兼容到C C ++中的坏主意功能的子集？我最感兴趣的是由包括核心语言推出差异，而不是标准库的答案。

Which features of C++ am I missing out on by restricting myself to a subset of features that are compatible to C? Why is restricting myself to a subset of features that are also compatible to C a bad idea in C++? I'm most interested in answers that encompass differences introduced by the core language, rather than the standard libraries.

有没有的更高效的替代纳入C $ C $ç成C ++项目比编译的C code口依靠与相同的C ++编译器我用它来编译我的C ++ code吗？什么时候应该使用C编译器？什么时候应该使用C ++编译器？有什么办法纳入C $ C $ç成C ++项目，即不使用C ++编译器编译C code涉及？这个在你的答案重点将特别有用。

Is there a more productive alternative to incorporate C code into a C++ project than compiling any C code I rely upon with the same C++ compiler I use to compile my C++ code? When should I use a C compiler? When should I use a C++ compiler? Is there any way to incorporate C code into a C++ project, that doesn't involve using the C++ compiler to compile C code? Emphasis on this in your answer would be particularly useful.

推荐答案

您问很多问题：

当我问我的C code的问题，有人告诉我不要投malloc的。这是在有保证的C ++编译C分配内存的唯一途径。为什么这是一个在C坏主意？为什么这是一个在C坏主意++？

When I ask questions about my C code, I'm told not to cast malloc. This is the only way to allocate memory in C that's guaranteed to compile in C++. Why is this a bad idea in C? Why is this a bad idea in C++?

铸造的返回值的malloc（）在C被认为是不好的，因为它可以隐藏的事实原型的malloc（）缺失。如果不投，编译器会提醒你，你需要的#include＆LT;＆stdlib.h中GT; 。演员是在C不必要的，因为语言允许隐式转换无效* 到另一个指针类型。

Casting the return value of malloc() in C is considered bad because it can hide the fact that the prototype to malloc() is missing. By not casting, the compiler will alert you that you need to #include <stdlib.h>. The cast is unnecessary in C, because the language allows for implicit conversion of void * to another pointer type.

铸件通常是不可取的。在C ++中有许多可用的机制，允许投要避免。例如，新和删除运营商，继承，多态和模板的C ++特性，可以利用来写类型安全code，而不需要铸造。

Casting is generally not desirable. In C++ there are many mechanisms available that allow casting to be avoided. For example, the new and delete operators, inheritance, polymorphism, and templates are features of C++ that can be leveraged to write type safe code without the need for casting.

的C其他功能我会通过限制自己的那些对C ++的兼容功能的一个子集上缺少哪一个呢？为什么限制自己的同时也是兼容C的特征的一个子集C ++中的坏主意？

Which other features of C am I missing out on by restricting myself to a subset of features that are compatible to C++? Why is restricting myself to a subset of features that are also compatible to C++ a bad idea in C?

我的头，C两种功能，可能是有用的，但在C ++中缺失会（1）聚合类型指定初始化，以及（2）变长数组的顶部。由于C是大多数是C ++的一个子集，我一般不找问题，使用C ++编译器为更强烈的类型安全的C，但你肯定不希望被写code，它是在一堆石膏投掷（类型安全就走出了窗外）。

Off the top of my head, two features of C that might be useful but are missing in C++ would be (1) designated initialization for aggregate types, and (2) variable length arrays. As C is mostly a subset of C++, I don't generally find an issue with using a C++ compiler as a "more strongly type-safe" C, but then you certainly don't want to be writing code that is throwing in a bunch of casts (type-safety goes out the window).

我会用C ++编译器来编译C code中的唯一情况是，如果有遗留的C code大基地，您作为开发商希望更新或功能的修改，这将是在C ++中更容易实现。

The only time I would use a C++ compiler to compile C code is if there was a large base of legacy C code, to which you as the developer wish to update or modify with functionality that would be more easily implemented in C++.

的C哪些功能++我会通过限制自己的是到C兼容功能的一个子集，错过了？为什么限制自己的同时也是兼容到C一个坏主意在C ++？

Which features of C++ am I missing out on by restricting myself to a subset of features that are compatible to C? Why is restricting myself to a subset of features that are also compatible to C a bad idea in C++?

您上C ++所提供的所有面向对象编程和泛型编程功能被淘汰出局。这样一来，你是不是能够正确地利用语言来充分利用。如果你想编写C code，最好是刚刚与C编译器坚持。

You lose out on all the object oriented and generic programming features that C++ has to offer. As a result, you are not able to properly leverage the language to full advantage. If you wish to write C code, it is better to just stick with a C compiler.

还有没有其他的选择吗？什么时候应该使用C编译器？什么时候应该使用C ++编译器？有什么办法纳入C $ C $ç成C ++项目，即不使用C ++编译器编译C code涉及？

Are there any other alternatives? When should I use a C compiler? When should I use a C++ compiler? Is there any way to incorporate C code into a C++ project, that doesn't involve using the C++ compiler to compile C code?

当然有替代品。您使用C code A C编译器和C ++编译器C ++ code。如果C和C ++编译器都来自同一供应商，那么在所有的可能性中，C ABI的两种编译器将是相同的。然后，如果你希望你的C ++ code到能够调用C函数，函数原型为这些功能只需要做广告，他们使用的是C ABI：

Of course there are alternatives. You use a C compiler for C code, and C++ compiler for C++ code. If the C and C++ compiler are from the same vendor, then in all likelihood, the C ABI for both compilers will be the same. Then, if you want your C++ code to be able to call C functions, the function prototypes to those functions just need to advertise that they are using the C ABI:

extern "C" {
/* the C function prototypes of the code compiled by the C compiler */
}

您可以通过使用C ++和C code包含相同的头文件中使用此使用 #IFDEF 来检查，看看是否code是由C ++编译器或不进行编译。

You can use this in the same header file included by both C++ and C code by using a #ifdef to check to see if the code is being compiled by a C++ compiler or not.

#ifdef __cplusplus
extern "C" {
#endif
/* ...the body of the C header file */
#ifdef __cplusplus
}
#endif

作为最后的警告，除非你有一个强烈的愿望，学习不同的语言，所以一般更富有成效使用您最熟悉的语言。如果有一个C ++编译器使用的要求，那么这将是最好的了解如何利用语言来你最大的利益。

As a final caveat, unless you have a burning desire to learn a different language, it is generally more productive to use the language that you are most familiar with. If there is a requirement that a C++ compiler be used, then it would be best to learn how to leverage the language to your maximum benefit.

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