# isystem

Specifies a directory to add to the start of the system include path.

## Syntax

Linux: | -isystem dir

macOS: | -isystem dir

Windows: | None

## Arguments

dir | Is the directory to add to the system include path.

## Default

OFF | The default system include path is used.

## Description

This option specifies a directory to add to the system include path. The compiler searches the specified directory for include files after it searches all directories specified by the -I compiler option but before it searches the standard system directories.

On Linux* systems, this option is provided for compatibility with gcc.

## IDE Equivalent

None

## Alternate Options

None

Parent topic: Preprocessor Options