xcode 如何将 C/C++ 函数添加到 Objective-C 代码中（iphone 相关）
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How to add C/C++ functions to Objective-C code (iphone related)
提问by cisgreat
I added .h/.cpp files with C functions to my Xcode project. How would I call a C function in an objective-C function?
我将带有 C 函数的 .h/.cpp 文件添加到我的 Xcode 项目中。我将如何在目标 C 函数中调用 C 函数？
When I included the C file (#import "example.h") in the app delegate header file it exploded with errors (could be that it treated the cpp file as objective-c) even though it compiles fine without being included/imported.
当我在应用程序委托头文件中包含 C 文件（#import“example.h”）时，它会因错误而爆炸（可能是它将 cpp 文件视为目标 c），即使它在没有被包含/导入的情况下编译得很好。
Thanks
谢谢
Edit: Renaming all the files from m to mm fixed the issue. However I am getting a linker error when building (ld: duplicate symbol)... Better research this first. Thanks again all.
编辑：将所有文件从 m 重命名为 mm 解决了该问题。但是，我在构建时遇到链接器错误（ld：重复符号）......最好先研究一下。再次感谢大家。
回答by LaC
If you want to use C++ with your Objective-C module, change the file extension from .mto .mm.
如果你想用C ++与Objective-C的模块，从改变文件扩展名.m来.mm。
回答by Joe
To use plain C in Objective-C just include the header/source file as usual and call the functions. The C files can use the standard extension
.hand.c. A lot of libraries are already used this way such as libxml and sqlite.To write C code that can use Objective-C (access FoundationFramework) it will need to be placed in a
.mfile. A.mfile can contain all C functions just like the main.m generated with new projects.To call C++ code the C++ can be in a
.cpp(or other valid extension) but your Objective-C file needs the extension.mmto call it, and once again simply include the header file. And to use Objective-C inside of a C++ class it will need the.mmextension.
要在 Objective-C 中使用普通 C，只需像往常一样包含头文件/源文件并调用函数。C 文件可以使用标准扩展名
.h和.c. 许多库已经以这种方式使用，例如 libxml 和 sqlite。要编写可以使用 Objective-C（访问 FoundationFramework）的 C 代码，需要将它放在一个
.m文件中。一个.m文件可以包含所有 C 函数，就像新项目生成的 main.m 一样。要调用 C++ 代码，C++ 可以位于
.cpp（或其他有效扩展名）中，但您的 Objective-C 文件需要扩展名.mm才能调用它，并且再次简单地包含头文件。并且要在 C++ 类中使用 Objective-C，它需要.mm扩展。
回答by Kristopher Johnson
C functions should be callable without doing anything special. Objective-C is a superset of C.
C 函数应该是可调用的，而无需做任何特殊的事情。Objective-C 是 C 的超集。
If the headers include C++ stuff, then you need to compile your files as Objective-C++ instead of Objective-C. To do this, just change the file extensions from .mto .mm.
如果头文件包含 C++ 内容，那么您需要将文件编译为 Objective-C++ 而不是 Objective-C。要做到这一点，只需更改从文件扩展名.m来.mm。
