环境相关

架构

if(CMAKE_SIZEOF_VOID_P EQUAL 8)
  set(_arch "x64")
else()
  set(_arch "Win32")
endif()

平台

IF (WIN32)
    MESSAGE(STATUS "Now is windows")
ELSEIF (APPLE)
    MESSAGE(STATUS "Now is Apple systens.")
ELSEIF (UNIX)
    MESSAGE(STATUS "Now is UNIX-like OS's.")
ENDIF ()