6.2. Solution File Format

Visual Studio 2008 actually creates two files for a solution, with extensions .suo and .sln (solution file). The first of these is a rather uninteresting binary file, and hence difficult to edit. It contains user-specific information — for example, which files were open when the solution was last closed, and the location of breakpoints. This file is marked as hidden, so it won't appear in the solution folder if you are using Windows Explorer unless you have enabled the option to show hidden files.

Occasionally the .suo file will become corrupted and cause unexpected behavior when you are building and editing applications. If Visual Studio becomes unstable for a particular solution, you should delete the .suo file. It will be recreated by Visual Studio the next time the solution is opened.

The .sln solution file contains information about the solution, such as the list of projects, the build configurations, and other settings that are not project-specific. Unlike many files used by Visual Studio 2008, the solution file is not an XML document. Instead, it stores information in blocks, as shown in the following example solution file:

Microsoft Visual Studio Solution File, Format Version 10.00
# Visual Studio 2008
Project("{F184B08F-C81C-45F6-A57F-5ABD9991F28F}") = "FirstProject",
    "FirstProjectFirstProject.vbproj", "{D4FAF2DD-A26C-444A-9FEE-2788B5F5FDD2}"
EndProject
Global
    GlobalSection(SolutionConfigurationPlatforms) = preSolution
         Debug|Any CPU = Debug|Any CPU
    EndGlobalSection
    GlobalSection(ProjectConfigurationPlatforms) = postSolution
     {D4FAF2DD-A26C-444A-9FEE-2788B5F5FDD2}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
     {D4FAF2DD-A26C-444A-9FEE-2788B5F5FDD2}.Debug|Any CPU.Build.0 = Debug|Any CPU
    EndGlobalSection
    GlobalSection(SolutionProperties) = preSolution
        HideSolutionNode = FALSE
    EndGlobalSection
EndGlobal

In this example the solution consists of a single project, FirstProject, and a Global section outlining settings that apply to the solution. For instance, the solution itself will be visible in the Solution Explorer because the HideSolutionNode setting is FALSE. If you were to change this value to TRUE, the solution name would not be displayed in Visual Studio.