# If _ MSC_VER & gt; 1000 # pragma once # endif

# If _ MSC_VER> 1000
# Pragma once
# Endif
Explanation:
This is Microsoft's pre-compilation control.
When _ MSC_VER is relatively small, it supports something different from the new version.

_ MSC_VER:
MS: Microsoft (Microsoft) Abbreviation
C: MSC is Microsoft's C compiler.
VER: Short for Version.
Together, the C compiler version of Microsoft
# Pragma once
Indicates that this file is included only once by the compiler during compilation! It is generally used in. h to prevent files from being repeatedly included!
# If _ MSC_VER> 1000
This statement is compiled if the vc compiler version is later than 1000! Versions earlier than 1000 are not supported # pragma
Once the statement www.2cto.com
 
Many header files contain
# If _ MSC_VER> 1000
# Pragma once
# Endif // _ MSC_VER> 1000
_ MSC_VER defines the compiler version. VC ++ 6.0 is 1200.
# If _ MSC_VER> 1000 means that if the compiler version is higher than 1000 (VC ++ 5.0)

Author: lxh1230119