How Does GCC Find Standard Include Files Like ``?

How GCC Locates Standard Include Files

GCC, the GNU Compiler Collection, has an extensive search path for standard include files. When users compile source files without explicitly specifying the path to includes like or , GCC can locate them seamlessly.

Default Include Paths

GCC maintains a list of default include directories to find standard headers. The paths are system-dependent and can be determined using the following commands:

• C:

  echo | gcc -xc -E -v -

• C :

  echo | gcc -xc++ -E -v -

The output of these commands provides a detailed list of the include paths and their priorities.

Path Configuration

The default include paths are configured through various mechanisms:

• Hardwired Paths: Certain paths, such as /usr/include on Linux systems, are hardcoded into the GCC compiler.
• System Configuration: The operating system may provide a standard set of include paths, which GCC will inherit.
• User Configuration: Users can override or supplement the default paths by setting environment variables like CPATH or INCLUDE.

Credit to Qt Creator Team

The discovery of GCC's include path determination process is attributed to the Qt Creator team. They have published a thorough guide that helps users understand the inner workings of GCC's include search mechanism.

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