Where is ptrdiff_t defined in C?

Question

Where is ptrdiff_t defined in C? If non-trivial, how can I make this type visible from GCC on Linux?

Answer 1

It's defined in stddef.h.

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That header defines the integral types size_t, ptrdiff_t, and wchar_t, the functional macro offsetof, and the constant macro NULL.

Answer 2

It is defined by the POSIX standard: http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stddef.h.html Where the type is exactly may be implemetation-specific, but interface is stddef.h

Answer 3

Since @Good Person said this wasn't specific to Linux, in Microsoft Visual Studio, ptrdiff_t is defined in:

C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\VC\Tools\MSVC\14.15.26726\include\vcruntime.h