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File extensions

Visual Studio

.sln (in container directory)

A Visual Studio solution file (.sln) is simply a container for projects, ie: it allows multiple projects to be grouped together.

Compare with project files (.csproj), which is a container for items in a project.


.suo (in container directory)

Visual Studio Solution User Options (.suo) file is hidden user configuration file stored in a binary format that is referenced by VSPackages created with Visual Studio; opened by the LoadUserOptions Method and modified by the WriteUserOptions and SaveUserOptions methods.  You should not add to source control.

If vs2010 debugger is slow, delete this file might help.

It is in the same folder as .sln file.

To display hidden files and folders.

1. Open Control Panel > Appearance and Personalization > Folder Options.

2. Click the View tab.

3. Under Advanced settings, click Show hidden files and folders, and then click OK.



The .user file is the other hidden user configurtion file which contains the user options for the project (while SUO is for the solution) and extends the project file name (Eg: anything.csproj.user contains user settings for the anything.csproj project).  You should not add to source control.


.csproj (in project folder)

c sharp project file.


.dll (in bin folder)

Dynamic link library.


.pdb (in bin folder)

A program database (PDB) file holds debugging and project state information that allows incremental linking of a Debug configuration of your program.

Created on: Monday, February 28, 2011 by Andrew Sin