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▶ Performance gab between using 'enum' and "using '#define' in Visual C++ 7.0
Environment : CPU: Intel 2.8G
Using enum:
Number of enum items := 100,000 -> compiling takes very long time.
Number of enum items := 10,000 -> very quick.
Using define
Very quick even if number of defined items reaches 100,000.
Experimentally,
if number of enum items are larger than specific threshold, compiling
performance of VC++ 7.0 drops dramatically. So in this case, we would
better to change 'enum' into '#define'.
▶ Order of finding 'include directory' in VC++ 7.0
"highest priority is directory where currently issued file is in.".
For example, lets consider following directory structure.
directory : xxx/src
=> a.c, c.h
directory : xxx/inc
=> b.h, c.h
(Let's assume that "xxx/inc" is added at "additional include directory").
"xxx/inc/b.h" and "xxx/inc/c.h" is used to compile "a.c". Even though
compiler try to compile "a.c", "b.h" is issued file during parsing
"b.h". And, "b.h" includes "c.h". So "c.h" in the directory where "b.h"
is in, is included, because currently issued file is "b.h".
▶ Case that '.c' file and '.cpp' file whose basename are same, are in one VC Project in Visual 2005 Express C++.
For example, if there are 'a.c' and 'a.cpp' in one project, MSVC
recognizes only '.cpp' file (based on experimental result). (I think the
reason is that default compiler of VC is 'cpp' compiler.)
So, even
if we modify 'a.c' and build, nothing is compiled because MSVC keep it's
eyes on 'a.cpp' - it is not changed. (--> It's MSVC's bug!!)
▶ There is no way to compile one file with several different options in VC project. So we should use 'command line' to do this.