CheckIncludeFileCXX

This module provides a command to check a C++ header file.

Load this module in a CMake project with:

include(CheckIncludeFileCXX)

Commands

This module provides the following command:

check_include_file_cxx

Checks once whether a header file exists and can be included in C++ code:

check_include_file_cxx(<include> <variable> [<flags>])

The arguments are:

<include>

A header file to be checked.

<variable>

The name of the variable to store the result of the check. This variable will be created as an internal cache variable.

<flags>

(Optional) A space-separated string of additional compilation flags to be added to the check. Alternatively, flags can be also specified with the CMAKE_REQUIRED_FLAGS variable below.

Variables Affecting the Check

The following variables may be set before calling this command to modify the way the check is run:

CMAKE_REQUIRED_FLAGS

A space-separated string of additional flags to pass to the compiler. A semicolon-separated list will not work. The contents of CMAKE_<LANG>_FLAGS and its associated configuration-specific CMAKE_<LANG>_FLAGS_<CONFIG> variables are automatically prepended to the compiler command before the contents of this variable.

CMAKE_REQUIRED_DEFINITIONS

A semicolon-separated list of compiler definitions, each of the form -DFOO or -DFOO=bar. A definition for the name specified by the result variable argument of the check command is also added automatically.

CMAKE_REQUIRED_INCLUDES

A semicolon-separated list of header search paths to pass to the compiler. These will be the only header search paths used; the contents of the INCLUDE_DIRECTORIES directory property will be ignored.

CMAKE_REQUIRED_LINK_OPTIONS

Added in version 3.14.

A semicolon-separated list of options to add to the link command (see try_compile() for further details).

CMAKE_REQUIRED_LIBRARIES

A semicolon-separated list of libraries to add to the link command. These can be the names of system libraries, or they can be Imported Targets (see try_compile() for further details).

CMAKE_REQUIRED_LINK_DIRECTORIES

Added in version 3.31.

A semicolon-separated list of library search paths to pass to the linker (see try_compile() for further details).

CMAKE_REQUIRED_QUIET

Added in version 3.1.

If this variable evaluates to a boolean true value, all status messages associated with the check will be suppressed.

Added in version 3.12: The CMAKE_REQUIRED_LIBRARIES variable, if policy CMP0075 is set to NEW.

Examples

Checking whether the C++23 header <stdfloat> exists and storing the check result in the HAVE_STDFLOAT_HEADER cache variable:

include(CheckIncludeFileCXX)

check_include_file_cxx(stdfloat HAVE_STDFLOAT_HEADER)

See Also

• The CheckIncludeFile module to check for single C header.
• The CheckIncludeFiles module to check for one or more C or C++ headers at once.