CODEWITHSUNDEEP
c++cinteropfortranfortran-iso-c-binding
user2023370
user2023370

Reputation: 11056

ISO_C_BINDING between different Fortran and C vendors

Is the concept of the Fortran ISO_C_BINDING module also supported by C/C++ compiler vendors? For example, the size of a C/C++ int can vary between the compilers from different vendors. So, with the ISO_C_BINDING module, we know that a Fortran C_INT type is 4 bytes; rather than merely having a kind of 4. But, we still don't know the size of an int in general in C/C++. Am I correct? Is there perhaps a standard C/C++ ISO_C_BINDING-compatible compiler switch?

Upvotes: 2

Views: 757

Answers (2)

Christoph
Christoph

Reputation: 169763

Most operating systems expose a C API, which obviously implies the existence of a standard C ABI on that platform. Normally, C compilers use this ABI, but there may be some peculiarities (eg, the standard calling convention for the Windows API is stdcall, which doesn't support variadic functions, thus there's a second major calling convention called cdecl).

The situation for C++ isn't as clear-cut: most operating system do not expose a C++ API (there are exceptions like BeOS/Haiku), thus compiler vendors were free to do whatever they thoght best, leading to incompatibilities between compilers from different vendors and sometimes even between different versions of the same compiler. I think at least GCC has stabilized their C++ ABI, but I have no idea about the general situation...

Upvotes: 2

haraldkl
haraldkl

Reputation: 3819

As far as I know, the standard only demands matching types in the same toolchain. Thus you are better using the C-Compiler from the same vendor. The standard doesn't claim anything about the sizes of the C_ kinds, I think.

Edit: Just looked it up in the standard, it is always talking about the companion C-compiler.

Upvotes: 5

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