C_STANDARD ---------- The C standard whose features are requested to build this target. This property specifies the C standard whose features are requested to build this target. For some compilers, this results in adding a flag such as ``-std=gnu11`` to the compile line. For compilers that have no notion of a standard level, such as Microsoft Visual C++ before 2015 Update 3, this has no effect. Supported values are ``90``, ``99`` and ``11``. If the value requested does not result in a compile flag being added for the compiler in use, a previous standard flag will be added instead. This means that using: .. code-block:: cmake set_property(TARGET tgt PROPERTY C_STANDARD 11) with a compiler which does not support ``-std=gnu11`` or an equivalent flag will not result in an error or warning, but will instead add the ``-std=gnu99`` or ``-std=gnu90`` flag if supported. This "decay" behavior may be controlled with the :prop_tgt:`C_STANDARD_REQUIRED` target property. Additionally, the :prop_tgt:`C_EXTENSIONS` target property may be used to control whether compiler-specific extensions are enabled on a per-target basis. See the :manual:`cmake-compile-features(7)` manual for information on compile features and a list of supported compilers. This property is initialized by the value of the :variable:`CMAKE_C_STANDARD` variable if it is set when a target is created.