问题
Where is ptrdiff_t defined in C? If non-trivial, how can I make this type visible from GCC on Linux?
回答1:
It's defined in stddef.h.
That header defines the integral types size_t, ptrdiff_t, and wchar_t, the functional macro offsetof, and the constant macro NULL.
回答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
回答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
来源：https://stackoverflow.com/questions/3597743/where-is-ptrdiff-t-defined-in-c