可以从C标准库函数在C ++中使用？ [英] Can functions from the C standard library be used in C++?

问题描述

现在我越来越熟悉C和C标准库，我不知道当我打开使用C ++的工作在以后的时间我在这方面的知识是有用的。

Right now I'm getting familiar with C and the C standard library and I wonder if my knowledge in this area will be useful when I turn to working with C++ at a later time.

因此​​，我想知道，我是否可以使用C标准库提供的功能在C ++环境，以及是否和为什么它会是有意义的其实这样做。

Therefore I'd like to know, whether I can use the functions provided by the C standard library in a C++ setting, and also whether and why it would make sense to actually do so.

推荐答案

是的，C ++最初的设计，使任何C语言库可以在C很容易地使用++。当然，这是略少真（特别是，如果C库恰巧使用像一些C ++的关键字尝试或的dynamic_cast ，它不会工作;同时，如果回调 $ C $在C ++ CD传递给C语言库产生异常，你很可能有一个大的混乱）。

Yes, C++ was originally designed so that any C library can be easily used in C++. Of course this is slightly less true (in particular, if a C library happens to use some C++ keyword like try or dynamic_cast, it won't work; also, if a callback coded in C++ passed to a C library is raising some exception, you are likely to have a big mess).

在C ++中使用C头文件中的标准做法是

The standard practice to use a C header file in C++ is

 extern "C" {
 #include <some_c_header_file.h>
 };

和大部分的现有的C头文件旨在与C ++合作，通过实际包含的东西，如

and most existing C header files are designed to cooperate with C++ by actually containing stuff like

 #ifdef __cplusplus
 extern "C" {
 #endif

 //// most of the header material goes here, C style

 #ifdef __cplusplus
 }; // end extern "C"
 #endif

在实践中，许多C标准头文件具有同等的C ++头包之类的东西上面（也包括空间std ）。例如c ＆LT; stdio.h中＆GT; 是C ++ ＆LT; cstdio＆GT; - 但你要经常preFER正品C ++流（＆LT; iostream的＆GT; ），但的printf 式的程序通常都比较的localization 的友好夹杂着的gettext （3）。

In practice, many C standard headers have equivalent C++ headers wrapping things like above (and also in namespace std). Eg C <stdio.h> is C++ <cstdio> -but you often should prefer genuine C++ streams (<iostream>), however printf-like routines are usually more localization friendly mixed with gettext(3).

然而 C和C ++是非常不同的语言您应该code在习惯C ++ 11（使用标准C ++的containers ，汽车的关闭的， RAII ，的智能指针，五的规则， SFINAE ，例外 匿名函数的，...）

However C and C++ are very different languages. You should code in idiomatic C++11 (using standard C++ containers, auto, closures, RAII, smart pointers, rule of five, SFINAE, exceptions, anonymous functions, ...)

一些标准的C函数不在地道Ç非常有用++。例如，你是不太可能使用的直接的的malloc 中的真正的C ++（至少preFER 新哪位还是非常低的水平，并没有更多的C ++神魂，更可能使用了大量的容器和智能指针的没有的堆与手动处理分配）。但 POSIX 功能（特别的系统调用（2） ....）在C非常有用++。 的longjmp 很可能是不符合C ++异常。

Some standard C functions are not very useful in idiomatic C++. For example, you are unlikely to use directly malloc in genuine C++ (at least prefer new -which is still very low level and no more in the C++ spirit-, more likely use a lot the containers and the smart pointers without dealing manually with heap allocation). But POSIX functions (notably syscalls(2) ....) are quite useful in C++. longjmp is likely to be incompatible with C++ exceptions.

BTW，C ++已经发展的很多的在本世纪。不学C ++ 98，但至少 C ++ 11 （还有的巨大的也许 C ++ 14 它们之间的差异）。使用的最近的编译器（ GCC 或的锵/ LLVM ）;在2015年12月，这意味着 GCC 5 至少还是的Clang/LLVM 3.7 最少。不要忘记，以使所有的警告和放大器;在编译调试信息（例如 G ++ -Wall -g -Wextra -std = C ++ 11 ）

BTW, C++ has evolved a lot in this century. Don't learn C++98 but at least C++11 (there are tremendous differences between them) and perhaps C++14. Use a recent compiler (GCC or Clang/LLVM); in december 2015, that means GCC 5 at least or Clang/LLVM 3.7 at least. Don't forget to enable all warnings & debug info in the compiler (e.g. g++ -Wall -Wextra -g -std=c++11)

C ++ （这意味着至少有C ++ 11）的是困难的编程语言后，相当多的复杂的比C是。你需要几个星期的阅读，了解一些了吧，和良好的编码风格和纪律是必要的（你可以很容易写的很蹩脚code在C ++中）。开始的编程：原理与放大器;练习使用C ++ 的

C++ (that means C++11 at least) is a difficult programming language, considerably more complex than C is. You'll need weeks of reading to learn some of it, and good coding style and discipline is essential (you can easily write very crappy code in C++). Start with Programming: Principles & Practice Using C++

我相信，如果你只知道C，阅读 SICP （和研究了一下计划）<前EM> 的学习C ++是值得的。

I believe that if you only know C, reading SICP (and studying a bit of Scheme) before learning C++ is worthwhile.

未定义行为的概念是非常重要的，无论是在C和用C可能更加++。你绝对需要了解它（见它C.Lattner的博客）和避免它。

The notion of undefined behavior is very important, both in C and probably even more in C++. You absolutely need to understand it (see C.Lattner's blog on it) and avoid it.

您也将通过研究（或许促成）某些现有的免费软件及其来源$学到很多大C $℃。因此，我建议使用Linux操作系统。

You will also learn a big lot by studying (and perhaps contributing to) some existing free software and its source code. Hence I recommend using Linux.

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