Question

众所周知,宣布<代码>extern “C”至C++功能使其名称具有C联系,使C代码能够链接。

我的问题是——是否有其他方案语言,我们能够使C++的功能名称与诸如<代码>extern“Lisp<>/code>或extern“FORTRAN”等内容联系起来?

如果不是,为什么? 什么是限制在<代码>C>后面的内部结构?

有哪些替代办法?

Answer 1

C++标准,7.5.2 dcl.link:

Linkage between C++ and non-C++ code fragments can be achieved using a linkage-specification:
linkage-specification:
    extern string-literal { declaration-seqopt}
    extern string-literal declaration
The string-literal indicates the required language linkage. This International Standard specifies the semantics for the string-literals "C" and "C++". Use of a string-literal other than "C" or "C++" is conditionally supported, with implementation-defined semantics. [ Note: Therefore, a linkage-specification with a string literal that is unknown to the implementation requires a diagnostic. —end note ] [ Note: It is recommended that the spelling of the string-literal be taken from the document defining that language. For example, Ada (not ADA) and Fortran or FORTRAN, depending on the vintage. —end note ]

因此,原则上,执行者可以选择支持C和C++以外的其他联系规格。

In practise however, on all modern platforms, C linkage is the lowest common denominator. As a general rule, these days, binary interop for languages other than C uses C linkage. On the widely used modern platforms, you will not see anything other than C and C++ linkage.

Answer 2

现代C++的编纂者不支持ISO C++标准所要求的“编码”和<代码>extern“C++”。与其他语文的结合最常用的是C呼唤公约和extern “C”。

And even when non-C calling conventions were supported, they often weren t selected by an extern string literal, they still used extern "C" but in conjunction with some non-standard calling convention declaration: for example, Microsoft C++ for 16-bit platforms (DOS, Windows 3.x, OS/2 1.x) used __pascal for the Pascal calling convention and __fortran for Fortran, instead of something like extern "Pascal" or extern "Fortran".

That said, IBM s contemporary C++ compilers for z/OS support extern "FORTRAN" for calling Fortran, extern "COBOL" for calling COBOL, and extern "PLI" for calling PL/I.

同样,IBM公司i 的ILE C++汇编者支持一份不同的<代码>extern清单。 stringlichs, see PDF page 338 of ILE C/C++ Programmer s Guide , such as extern "RPG", extern "C nowiden” (即extern "C",但转而转而通过,因此,short将实际作为2条而不是4条通过),(从而使IBM的遗产前ILE打公约)。

现在看来,IBM是唯一支持非<条码>C”的C++主要供应商。

友情链接