Questions tagged [.net]

Do NOT use for questions about .NET Core - use [.net-core] instead. The .NET framework is a software framework designed mainly for the Microsoft Windows operating system. It includes an implementation of the Base Class Library, Common Language Runtime (commonly referred to as CLR), Common Type System (commonly referred to as CTS) and Dynamic Language Runtime. It supports many programming languages, including C#, VB.NET, F# and C++/CLI.

The .NET Framework is not specific to any programming language. Programming languages from Microsoft, like , , CLI, and , as well as many other languages from other vendors, all use the same .NET Framework.

The .NET Framework includes a large library of functions as part of the Base Class Library (BCL), including those related to user interface design, data access, database connectivity, cryptography, development of web applications, mathematical algorithms, and network communications. This extensive library simplifies development and makes it easy to rapidly develop new applications.

As such, questions like "How do I do file I/O in C#?" should really be "How do I do file I/O with .NET?". Because such a question concerns the file I/O libraries provided by the .NET Framework, it should be tagged with both the tag, and with the tag, to indicate that you'd like the answer to be written in the C# programming language.

See also: , (do NOT use the tag for questions about .NET Core).

Getting help

Versions of .NET


Garbage collector

Free .NET Programming Books (C# / F# / VB / Nemerle / Visual Studio)

Reference Source

API Guide


Database Drivers

  • MySQL Connector - Connector/Net is a fully-managed ADO.NET driver for MySQL
  • Npgsql - .NET data provider for PostgreSQL
  • MongoDB - Official MongoDB C# driver
  • RethinkDb.Driver - A RethinkDB database driver in C# striving for 100% ReQL API compatibility and completeness.
  • ServiceStack Redis - .NET's leading C# Redis client
  • StackExchange Redis - General purpose Redis client from Stack Exchange
  • Cassandra - DataStax .NET driver for Apache Cassandra
  • Couchbase - Official Couchbase .NET client library, based on the Enyim Memcached client
  • Firebird.NET - The .NET Data provider is written in C# and provides a high-performance, native implementation of the Firebird API

Useful .NET Libraries


  • Math.NET Numerics - special functions, linear algebra, probability models, random numbers, interpolation, integral transforms and more

Package managers for external libraries

  • NuGet (formerly known as NuPack) - Microsoft (developer-focused package management system for the .NET platform intent on simplifying the process of incorporating third-party libraries into a .NET application during development)

Build Tools

  • Prebuild - Generate project files for all Visual Studio versions, including major IDEs and tools like SharpDevelop, MonoDevelop, NAnt and Autotools

Dependency Injection/Inversion of Control



Design by Contract



Data Mapper



PDF Creators/Generators

Unit Testing/Mocking

Automated Web Testing

Misc Testing/Quality Support/Behavior Driven Development (BDD)

URL Rewriting

Web Debugging

  • Glimpse - Firebug for your webserver


MS Word/Excel Documents Manipulation

  • DocX to create, read, manipulate formatted word documents. Easy syntax, working nicely, actively developed. No Microsoft Office necessary.
  • Excel XML Writer allows creation of .XLS (Excel) files. No Microsoft Office necessary. It has been a while since it has been updated. It also provides a code generator to create code from already created XLS file (saved as XML). Haven't tested this but looks very promising. The author hasn't updated this in awhile.
  • Excel Reader allows creation/reading of .XLS (Excel) files. No Microsoft Office necessary. It has been awhile since it has been updated.
  • Excel Package allows creation/reading of .XLSX (Excel 2007) files. No Microsoft Office necessary. The author is gone, so it's out of date.
  • EPPlus is based on Excel Package and allows creation/reading of .XLSX (Excel 2007). It is actually the most advanced even comparing to NPOI.
  • NPOI is the .NET version of POI Java project at POI is an open source project which can help you read/write Excel, Word, and PowerPoint files. Latest sources available at GitHub repository


  • sharpSerializer - XML/binary serializer for WPF, ASP.NET AND Silverlight
  • protobuf-net - .NET implementation of Google's cross-platform binary serializer (for all .NET platforms)

Machine learning

  • Encog C# - Neural networks
  • - AI, computer vision, genetic algorithms, machine learning

Chat room

Chat about .NET with other Stack Overflow users

RESTFul Web Services

  • RestSharp - Simple REST and HTTP API Client for .NET


333813 questions
66 answers

What is the difference between String and string in C#?

What are the differences between these two, and which one should I use? string s = "Hello world!"; String s = "Hello world!";
Lance Fisher
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34 answers

How to enumerate an enum?

How can you enumerate an enum in C#? E.g. the following code does not compile: public enum Suit { Spades, Hearts, Clubs, Diamonds } public void EnumerateAllSuitsDemoMethod() { foreach (Suit suit in Suit) { …
Ian Boyd
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13 answers

What are the correct version numbers for C#?

What are the correct version numbers for C#? What came out when? Why can't I find any answers about C# 3.5? This question is primarily to aid those who are searching for an answer using an incorrect version number, e.g. C# 3.5. The hope is that…
Jon Skeet
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59 answers

Deep cloning objects

I want to do something like: MyObject myObj = GetMyObj(); // Create and fill a new object MyObject newObj = myObj.Clone(); And then make changes to the new object that are not reflected in the original object. I don't often need this functionality,…
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29 answers

Catch multiple exceptions at once?

It is discouraged to simply catch System.Exception. Instead, only the "known" exceptions should be caught. Now, this sometimes leads to unnecessary repetitive code, for example: try { WebId = new Guid(queryString["web"]); } catch…
Michael Stum
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18 answers

Difference between decimal, float and double in .NET?

What is the difference between decimal, float and double in .NET? When would someone use one of these?
15 answers

Should 'using' directives be inside or outside the namespace in C#?

I have been running StyleCop over some C# code, and it keeps reporting that my using directives should be inside the namespace. Is there a technical reason for putting the using directives inside instead of outside the namespace?
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41 answers

How do I get a consistent byte representation of strings in C# without manually specifying an encoding?

How do I convert a string to a byte[] in .NET (C#) without manually specifying a specific encoding? I'm going to encrypt the string. I can encrypt it without converting, but I'd still like to know why encoding comes to play here. Also, why should…
Agnel Kurian
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74 answers

How do I calculate someone's age based on a DateTime type birthday?

Given a DateTime representing a person's birthday, how do I calculate their age in years?
Jeff Atwood
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47 answers

How do I create an Excel (.XLS and .XLSX) file in C# without installing Microsoft Office?

How can I create an Excel spreadsheet with C# without requiring Excel to be installed on the machine that's running the code?
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111 answers

How do I remedy "The breakpoint will not currently be hit. No symbols have been loaded for this document." warning?

A C# desktop application (on the Visual Studio Express edition) worked, but then it didn't work 5 seconds later. I tried the following: Ensure debug configuration, debug flag, and full debug information are set on all assemblies. Delete all bin and…
Instance Hunter
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26 answers

What is a NullReferenceException, and how do I fix it?

I have some code and when it executes, it throws a NullReferenceException, saying: Object reference not set to an instance of an object. What does this mean, and what can I do to fix this error?
John Saunders
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20 answers

Proper use of the IDisposable interface

I know from reading Microsoft documentation that the "primary" use of the IDisposable interface is to clean up unmanaged resources. To me, "unmanaged" means things like database connections, sockets, window handles, etc. But, I've seen code where…
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10 answers

Calling the base constructor in C#

If I inherit from a base class and want to pass something from the constructor of the inherited class to the constructor of the base class, how do I do that? For example, if I inherit from the Exception class I want to do something like this: class…
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8 answers

How to loop through all enum values in C#?

This question already has an answer here: How do I enumerate an enum in C#? 26 answers public enum Foos { A, B, C } Is there a way to loop through the possible values of Foos? Basically? foreach(Foo in Foos)
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