# Command-line build with csc.exe

You can invoke the C# compiler by typing the name of its executable file (csc.exe) at a command prompt.

If you use the Developer Command Prompt for Visual Studio window, all the necessary environment variables are set for you. For information on how to access this tool, see the Developer Command Prompt for Visual Studio topic.

If you use a standard Command Prompt window, you must adjust your path before you can invoke csc.exe from any subdirectory on your computer. You also must run vsvars32.bat to set the appropriate environment variables to support command-line builds. For more information about vsvars32.bat, including instructions for how to find and run it, see How to: Set Environment Variables for the Visual Studio Command Line.

If you're working on a computer that has only the Windows Software Development Kit (SDK), you can use the C# compiler at the SDK Command Prompt, which you open from the Microsoft .NET Framework SDK menu option.

You can also use MSBuild to build C# programs programmatically. For more information, see MSBuild.

The csc.exe executable file usually is located in the Microsoft.NET\Framework\<Version> folder under the Windows directory. Its location might vary depending on the exact configuration of a particular computer. If more than one version of the .NET Framework is installed on your computer, you'll find multiple versions of this file. For more information about such installations, see How to: determine which versions of the .NET Framework are installed.

Tip

When you build a project by using the Visual Studio IDE, you can display the csc command and its associated compiler options in the Output window. To display this information, follow the instructions in How to: View, Save, and Configure Build Log Files to change the verbosity level of the log data to Normal or Detailed. After you rebuild your project, search the Output window for csc to find the invocation of the C# compiler.

In this topic

## Rules for command-line syntax for the C# compiler

The C# compiler uses the following rules when it interprets arguments given on the operating system command line:

• Arguments are delimited by white space, which is either a space or a tab.

• The caret character (^) is not recognized as an escape character or delimiter. The character is handled by the command-line parser in the operating system before it's passed to the argv array in the program.

• A string enclosed in double quotation marks ("string") is interpreted as a single argument, regardless of white space that is contained within. A quoted string can be embedded in an argument.

• A double quotation mark preceded by a backslash (\") is interpreted as a literal double quotation mark character (").

• Backslashes are interpreted literally, unless they immediately precede a double quotation mark.

• If an even number of backslashes is followed by a double quotation mark, one backslash is put in the argv array for every pair of backslashes, and the double quotation mark is interpreted as a string delimiter.

• If an odd number of backslashes is followed by a double quotation mark, one backslash is put in the argv array for every pair of backslashes, and the double quotation mark is "escaped" by the remaining backslash. This causes a literal double quotation mark (") to be added in argv.

## Sample command lines for the C# compiler

• Compiles File.cs producing File.exe:
csc File.cs

• Compiles File.cs producing File.dll:
csc -target:library File.cs

• Compiles File.cs and creates My.exe:
csc -out:My.exe File.cs

• Compiles all the C# files in the current directory with optimizations enabled and defines the DEBUG symbol. The output is File2.exe:
csc -define:DEBUG -optimize -out:File2.exe *.cs

• Compiles all the C# files in the current directory producing a debug version of File2.dll. No logo and no warnings are displayed:
csc -target:library -out:File2.dll -warn:0 -nologo -debug *.cs

• Compiles all the C# files in the current directory to Something.xyz (a DLL):
csc -target:library -out:Something.xyz *.cs


## Differences between C# compiler and C++ compiler output

There are no object (.obj) files created as a result of invoking the C# compiler; output files are created directly. As a result of this, the C# compiler does not need a linker.