问题
I was wondering why C's and C++'s FILE type is spelled with capital letters. Other types are spelled with lower case letters.
Edit see § 27.9.2 of C++11, table 134
回答1:
In very old dialects of C, before there was any of standardization, when the FILE type was invented, and before typedef existed, that name was a macro:
#define FILE struct _iobuf
The convention was to have macros named in all uppercase.
http://minnie.tuhs.org/cgi-bin/utree.pl?file=V7/usr/include/stdio.h
(the macros that were in lowercase were simply optimized versions of functions - many of them also existed as proper functions)
来源：https://stackoverflow.com/questions/8281775/why-is-stdfile-in-capital-letters