source-line-file-path-identifiers.md

title	description	keywords	author	manager	ms.date	ms.topic	ms.prod	ms.technology	ms.assetid
Source Line, File, and Path Identifiers (F#)	Source Line, File, and Path Identifiers (F#)	visual f#, f#, functional programming	dend	danielfe	05/16/2016	language-reference	visual-studio-dev14	devlang-fsharp	4cfe7439-275c-4d08-980b-784e240bbf29

Source Line, File, and Path Identifiers

The identifiers __LINE__, __SOURCE_DIRECTORY__ and __SOURCE_FILE__ are built-in values that enable you to access the source line number, directory and file name in your code.

Syntax

__LINE__
__SOURCE_DIRECTORY__
__SOURCE_FILE__

Remarks

Each of these values has type string.

The following table summarizes the source line, file, and path identifiers that are available in F#. These identifiers are not preprocessor macros; they are built-in values that are recognized by the compiler.

Predefined identifier	Description
__LINE__	Evaluates to the current line number, considering #line directives.
__SOURCE_DIRECTORY__	Evaluates to the current full path of the source directory, considering #line directives.
__SOURCE_FILE__	Evaluates to the current source file name and its path, considering #line directives.
For more information about the #line directive, see Compiler Directives.

Example

The following code example demonstrates the use of these values.

[!code-fsharpMain]

Output:

Line: 4
Source Directory: C:\Users\username\Documents\Visual Studio 2010\Projects\SourceInfo\SourceInfo
Source File: C:\Users\username\Documents\Visual Studio 2010\Projects\SourceInfo\SourceInfo\Program.fs

See Also

Compiler Directives

F# Language Reference