_MSC_VER

_MSC_VER 是什么意思？

这是微软的预编译控制。
在_MSC_VER较小时，它对一些东西的支持与新版不同

_MSC_VER分解如下：

MS：Microsoft（微软）的简写

C：MSC就是Microsoft出的C编译器。

VER：Version（版本）的简写。

全部加在一起就是：Microsoft的C编译器的版本

很多头文件中有

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

_MSC_VER 定义编译器的版本，VC++6.0就是1200  
#if   _MSC_VER   >   1000的意思就是如果编译器版本高于1000（VC++5.0）

4C:\Documents and Settings\Administrator>cl /?
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8168 for 80x86
Copyright (C) Microsoft Corp 1984-1998. All rights reserved.

                          C/C++ COMPILER OPTIONS

                              -OPTIMIZATION-

/O1 minimize space                       /Op[-] improve floating-pt consistency
/O2 maximize speed                       /Os favor code space
/Oa assume no aliasing                   /Ot favor code speed
/Ob<n> inline expansion (default n=0)    /Ow assume cross-function aliasing
/Od disable optimizations (default)      /Ox maximum opts. (/Ogityb1 /Gs)
/Og enable global optimization           /Oy[-] enable frame pointer omission
/Oi enable intrinsic functions

                             -CODE GENERATION-

/G3 optimize for 80386                   /Gy separate functions for linker
/G4 optimize for 80486                   /Ge force stack checking for all funcs
/G5 optimize for Pentium                 /Gs[num] disable stack checking calls
/G6 optimize for Pentium Pro             /Gh enable hook function call
/GB optimize for blended model (default) /GR[-] enable C++ RTTI
/Gd __cdecl calling convention           /GX[-] enable C++ EH (same as /EHsc)
/Gr __fastcall calling convention        /Gi[-] enable incremental compilation
/Gz __stdcall calling convention         /Gm[-] enable minimal rebuild
/GA optimize for Windows Application     /EHs enable synchronous C++ EH
/GD optimize for Windows DLL             /EHa enable asynchronous C++ EH
(press <return> to continue)
/Gf enable string pooling                /EHc extern "C" defaults to nothrow
/GF enable read-only string pooling      /QIfdiv[-] enable Pentium FDIV fix
/GZ enable runtime debug checks          /QI0f[-] enable Pentium 0x0f fix

                              -OUTPUT FILES-

/Fa[file] name assembly listing file     /Fo<file> name object file
/FA[sc] configure assembly listing       /Fp<file> name precompiled header file
/Fd[file] name .PDB file                 /Fr[file] name source browser file
/Fe<file> name executable file           /FR[file] name extended .SBR file
/Fm[file] name map file

                              -PREPROCESSOR-

/C don't strip comments                  /FI<file> name forced include file
/D<name>{=|#}<text> define macro         /U<name> remove predefined macro
/E preprocess to stdout                  /u remove all predefined macros
/EP preprocess to stdout, no #line       /I<dir> add to include search path
/P preprocess to file                    /X ignore "standard places"

                                -LANGUAGE-

/Zi enable debugging information         /Zl omit default library name in .OBJ
/ZI enable Edit and Continue debug info /Zg generate function prototypes
(press <return> to continue)
/Z7 enable old-style debug info          /Zs syntax check only
/Zd line number debugging info only      /vd{0|1} disable/enable vtordisp
/Zp[n] pack structs on n-byte boundary   /vm<x> type of pointers to members
/Za disable extensions (implies /Op)     /noBool disable "bool" keyword
/Ze enable extensions (default)

                              -MISCELLANEOUS-

/?, /help print this help message        /V<string> set version string
/c compile only, no link                 /w disable all warnings
/H<num> max external name length         /W<n> set warning level (default n=1)
/J default char type is unsigned         /WX treat warnings as errors
/nologo suppress copyright message       /Yc[file] create .PCH file
/Tc<source file> compile file as .c      /Yd put debug info in every .OBJ
/Tp<source file> compile file as .cpp    /Yu[file] use .PCH file
/TC compile all files as .c              /YX[file] automatic .PCH
/TP compile all files as .cpp            /Zm<n> max memory alloc (% of default)

                                 -LINKING-

/MD link with MSVCRT.LIB                 /MDd link with MSVCRTD.LIB debug lib
/ML link with LIBC.LIB                   /MLd link with LIBCD.LIB debug lib
/MT link with LIBCMT.LIB                 /MTd link with LIBCMTD.LIB debug lib
/LD Create .DLL                          /F<num> set stack size
(press <return> to continue)
/LDd Create .DLL debug libary            /link [linker options and libraries]

C:\Documents and Settings\Administrator>