INCLUDEPATH

Includepath is a term used in software development to describe a collection of directory paths that a compiler, interpreter, or build system searches for include or import files. The concept helps tools locate header files, modules, or other resources that are not in the current working directory. While the exact spelling and usage vary by tool, includepath broadly refers to the include search path used during compilation or linking.

In compilers and build systems, includepath is commonly implemented as a set of directories added to the default search paths. For example, C and C++ compilers often use an include path configured with options such as -I in GCC and Clang, or with project settings in an integrated development environment. CMake and other build systems provide mechanisms to declare include directories so that targets can find headers during build. In Visual Studio, similar behavior is exposed through Additional Include Directories in project properties. Other languages and environments may refer to the concept as include directories, search paths, or module paths, each with its own syntax.

The order and contents of an includepath affect which files are found and which files take precedence if multiple matches exist. Incorrect or missing paths typically cause compilation errors, such as “file not found.” Paths may be absolute or relative, and may require platform-specific separators. Environment variables (for example CPATH or C_INCLUDE_PATH in Unix-like systems) can provide default includepath values shared across tools.

See also: include directive, header search path, include directories, module resolution.