GetOpts.NET 1.3.0

.NET 8.0 This package targets .NET 8.0. The package is compatible with this framework or higher. .NET Standard 2.0 This package targets .NET Standard 2.0. The package is compatible with this framework or higher. .NET Framework 4.5 This package targets .NET Framework 4.5. The package is compatible with this framework or higher. 
dotnet add package GetOpts.NET --version 1.3.0
                    


                    

                
NuGet\Install-Package GetOpts.NET -Version 1.3.0
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package. 
<PackageReference Include="GetOpts.NET" Version="1.3.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package. 
<PackageVersion Include="GetOpts.NET" Version="1.3.0" />
                    


                            Directory.Packages.props
                        

                    

                
<PackageReference Include="GetOpts.NET" />
                    


                            Project file
For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package. 
paket add GetOpts.NET --version 1.3.0
                    


                    

                
#r "nuget: GetOpts.NET, 1.3.0"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package. 
#:package GetOpts.NET@1.3.0
#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package. 
#addin nuget:?package=GetOpts.NET&version=1.3.0
                    


                            Install as a Cake Addin
                        

                    

                
#tool nuget:?package=GetOpts.NET&version=1.3.0
                    


                            Install as a Cake Tool

GetOpts.NET

A callback-based program option parser for C#.

Description
ASSEMBLY NAME: GetOpts.NET
CREATED BY: Latency McLaughlin
UPDATED: 10/18/2026
FRAMEWORKS: net45, net451, net452, net46, net461, net462, net47, net471, net472, net48, net481, netstandard2.0, netstandard2.1, net8.0, net9.0, net10.0, net11.0
LANGUAGE: C# preview
OUTPUT TYPE: Library API
SUPPORTS: Visual Studio
GFX SUBSYS: [None]
TAGS: [GetOpt C#]
STATUS: workflow-badge
LICENSE: license-badge
VERSION: 1.3.0

Introduction

This project features a callback-based option parser for C#. It takes advantage of C# features such as collection initializers and lambda delegates to provide a short, concise specification of the option names to parse, whether or not those options support values, and what to do when the option is encountered.

An OptionSet is created with one entry per option: a |-separated list of names (v|verbose), an optional = suffix when the option takes a value (n|name=), and a callback that runs when the option is encountered. The callback receives the value, or null when the option has none.

History

See: getopt

Usage

Declaring options

Options are declared with a collection initializer or with chained Add calls. Each entry is a |-separated list of names, an optional value suffix, and a callback.

var verbose   = 0;
var showHelp  = false;
var names     = new List<string>();

var p = new OptionSet
{
	{ "v|verbose", v => { if (v != null) ++verbose; } },
	{ "h|?|help",  v => showHelp = v != null },
	{ "n|name=",   v => names.Add(v!) },
};

var p = new OptionSet()
	.Add("v|verbose", v => { if (v != null) ++verbose; })
	.Add("h|?|help",  v => showHelp = v != null)
	.Add("n|name=",   v => names.Add(v!));

Parsing arguments

Parse runs the callbacks and returns the arguments that were not consumed by any option.

List<string> extra = p.Parse(["-v", "--name=Alice", "-n", "Bob", "file1.txt", "file2.txt"]);
// verbose == 1, names == ["Alice", "Bob"], extra == ["file1.txt", "file2.txt"]

Everything after a lone -- is treated as unprocessed.

Prototype syntax

Prototype Meaning
v\|verbose Flag. The callback receives the option name, or null for -v-.
n\|name= Required value.
l\|library: Optional value. The callback receives null when no value is given.
D= with two parameters Key/value pair, e.g. -DNAME=value.
<> Default handler. It receives every argument that is not an option.

Values can be supplied as -name=value, -name:value, --name value, or /name value. Single-character flags can be bundled (-abc), and a value option may end a bundle (-vfFILE).

Boolean options

A flag followed by + or - turns it on or off. In the callback, a null value means the option was disabled.

var debug = false;
var p = new OptionSet { { "debug", v => debug = v != null } };

p.Parse(["-debug"]);   // debug == true
p.Parse(["-debug+"]);  // debug == true
p.Parse(["-debug-"]);  // debug == false

Typed values

The generic Add<T> overload converts the value using the type's TypeConverter. A failed conversion throws OptionException.

var port    = 80;
var timeout = TimeSpan.Zero;

var p = new OptionSet
{
	{ "port=",    (int v)      => port    = v },
	{ "timeout=", (TimeSpan v) => timeout = v },
};

p.Parse(["--port=8080", "--timeout=00:00:30"]);

Key/value options

Use the two-type Add<TKey, TValue> overload for options that take a key and a value.

var defines = new Dictionary<string, int>();

var p = new OptionSet
{
	{ "D=", (string k, int v) => defines.Add(k, v) },
};

p.Parse(["-DWIDTH=80", "-D", "HEIGHT=24"]);

Help text

Pass a description as the second argument, then call WriteOptionDescriptions.

var p = new OptionSet
{
	{ "n|name=", "the {NAME} of the user", v => name = v },
	{ "v",       "increase message verbosity", v => ++verbosity },
	{ "h|help",  "show this message and exit", v => showHelp = v != null },
};

p.WriteOptionDescriptions(Console.Out);

  -n, --name=NAME            the NAME of the user
  -v                         increase message verbosity
  -h, --help                 show this message and exit

Error handling

Invalid input throws OptionException, for example a missing required value or an unconvertible value. OptionException.OptionName holds the offending option.

try
{
	p.Parse(args);
}
catch (OptionException e)
{
	Console.Error.WriteLine($"{e.OptionName}: {e.Message}");
}

Installation

This library can be installed from NuGet.

Report An Issue

If you have a patch to contribute, a feature to request, or a bug to report, please post to the Issue Tracker.

Donation

Click the button to donate to my efforts: Donate via Paypal

License

The source code for the site is licensed under the MIT license, which you can find in the MIT-LICENSE.txt file.

Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 was computed.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 is compatible.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed.  net9.0 is compatible.  net9.0-android was computed.  net9.0-browser was computed.  net9.0-ios was computed.  net9.0-maccatalyst was computed.  net9.0-macos was computed.  net9.0-tvos was computed.  net9.0-windows was computed.  net10.0 is compatible.  net10.0-android was computed.  net10.0-browser was computed.  net10.0-ios was computed.  net10.0-maccatalyst was computed.  net10.0-macos was computed.  net10.0-tvos was computed.  net10.0-windows was computed.  net11.0 is compatible. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 is compatible. 
.NET Framework net45 is compatible.  net451 is compatible.  net452 is compatible.  net46 is compatible.  net461 is compatible.  net462 is compatible.  net463 was computed.  net47 is compatible.  net471 is compatible.  net472 is compatible.  net48 is compatible.  net481 is compatible. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
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Version Downloads Last Updated
1.3.0 85 10/19/2026

Update target frameworks to include .NET 11.0 and refactor namespace.