enable_language(CXX) # Write value of `SET_CHARSET` for comparison later. file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/set_charset.txt" "${SET_CHARSET}") # Set macro which determines the character-set. if("${SET_CHARSET}" STREQUAL "MultiByte") add_compile_definitions(_MBCS=1) endif() if("${SET_CHARSET}" STREQUAL "NotSet") add_compile_definitions(_SBCS=1) endif() if("${SET_CHARSET}" STREQUAL "Unicode") add_compile_definitions(_UNICODE=1) endif() add_library(foo foo.cpp)