.CS File Extension

C# Source Code File

Developer Microsoft
4.3  |  377 Votes
NEW: Open your .CS file online with File Helper.View Online

What is a CS file?

A CS file is a source code file written in C# (pronounced "C Sharp"), an object-oriented programming language created by Microsoft for use with .NET Framework and .NET (successor to .NET Framework). It is used for developing a range of applications, from simple desktop programs to applications for distributed environments.

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Screenshot of a .cs file in Adobe Dreamweaver CC 2019
CS file open in Adobe Dreamweaver CC 2019

Developers utilize C# for building applications that run in the .NET ecosystem, which is a software framework that provides a standard method for building and deploying applications (primarily in Windows). The programming language is component-oriented, and some of its features include nullable types, exception handling, garbage collection, lambda expressions, asynchronous operations, and Language Integrated Query (LINQ) syntax. It also is flexible (through versioning) to ensure compatibility as technologies evolve.

Microsoft developed C# in 2000, and Ecma approved it as an international standard in 2002. It was originally released with .NET Framework 1.0 and included with Visual Studio .NET 2002.

Throughout the years, Microsoft has released numerous versions of C# with .NET Framework and Visual Studio. Some notable releases:

  • C# 2.0 - November 2005 - .NET Framework 2.0 and Visual Studio 2005
  • C# 3.0 - November 2007 - .NET Framework 2.0-3.5 and Visual Studio 2008
  • C# 4.0 - April 2010 - .NET Framework 4.0 and Visual Studio 2010
  • C# 5.0 - August 2012 - .NET Framework 4.5 and Visual Studio 2012 and 2013
  • C# 6.0 - July 2015 - .NET Framework 4.6 and Visual Studio 2015
  • C# 7.0 - March 2017 - .NET Framework 4.7 and Visual Studio 2017
  • C# 8.0 - September 2019 - .NET Core 3.0-3.1 and Visual Studio 2019 (16.3)
  • C# 9.0 - September 2020 - .NET 5.0 and Visual Studio 2019 (16.8)

NOTE: When C# programs are compiled, they can then be run by the Common Language Runtime (CLR) included with the .NET Framework.

How to open a CS file

You can open and edit CS files with Visual C#, a Microsoft Visual Studio component. You can also edit the files with various other source code editors that feature syntax highlighting, such as the cross-platform Microsoft Visual Studio Code.

CS files may be opened and edited with basic text editors, including Microsoft Notepad++ (bundled with Windows) or Apple TextEdit (bundled with macOS). However, plain text editors are not good options for editing the files since they do not support the syntax structure.

If you are looking to compile CS files, Mono is a common choice and is open source and cross-platform.

Programs that open CS files

CLEO Custom Script

Developer CLEO
4.2  |  127 Votes

A CS file may also be a custom script used by CLEO 3 and 4, which are mod loaders for Grand Theft Auto: San Andreas. It contains commands used to modify GTA: San Andreas's gameplay. GTA modders often distribute CS files online, for other players to download and use.

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CLEO 3 and 4 are third-party applications that players can use to install mods for GTA: San Andreas. These mods are saved as CLEO custom scripts (CS files) or plug-ins (.CLEO files).

Typically, CS files contain commands that add features to GTA: San Andreas. In some cases, CS files may alter gameplay in other ways. To create CS files, modders use Sanny Builder, a custom script editor and compiler.

NOTE: Some CLEO custom scripts may be saved as CS3 files. These files are CLEO 3 scripts that can be used with CLEO 4 via the program's "legacy mode."

How to open a CS file

To use a CS file with Grand Theft Auto: San Andreas (Windows), players must:

  1. Install CLEO 4 (using the instructions found in the program's README.md file).
  2. Locate the cleo directory added to GTA: San Andreas's installation directory.
  3. Place the CS file in the cleo directory.

GTA: San Andreas modders can also open CS files with Sanny Builder, to view and edit their contents.

Programs that open or reference CS files


ColorSchemer Studio Color Scheme

Developer CHROMAom
3.5  |  35 Votes

File created by ColorSchemer Studio, a program used for developing color palettes for websites, magazines, home decoration, and other target mediums; saves the user's color schemes, which often contain complementary colors that are matched with one another on the color spectrum.

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NOTE: CHROMAom ColorSchemer Studio has been discontinued.

Programs that open CS files

CHROMAom ColorSchemer Studio

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