# CXXFLAGS

New in version 3.10.

This is a CMake Environment Variable. Its initial value is taken from the calling process environment.

Default compilation flags to be used when compiling `CXX` (C++) files. Will only be used by CMake on the first configuration to determine `CXX` default compilation flags, after which the value for `CXXFLAGS` is stored in the cache as `CMAKE_CXX_FLAGS`. For any configuration run ( including the first), the environment variable will be ignored if the `CMAKE_CXX_FLAGS` variable is defined.

See also `CMAKE_CXX_FLAGS_INIT`.