How do I programmatically list all projects in a solution?

Here's a PowerShell script that retrieves project details from a .sln file:

Get-Content 'Foo.sln' |
  Select-String 'Project\(' |
    ForEach-Object {
      $projectParts = $_ -Split '[,=]' | ForEach-Object { $_.Trim('[ "{}]') };
      New-Object PSObject -Property @{
        Name = $projectParts[1];
        File = $projectParts[2];
        Guid = $projectParts[3]
      }
    }

    var Content = File.ReadAllText(SlnPath);
    Regex projReg = new Regex(
        "Project\\(\"\\{[\\w-]*\\}\"\\) = \"([\\w _]*.*)\", \"(.*\\.(cs|vcx|vb)proj)\""
        , RegexOptions.Compiled);
    var matches = projReg.Matches(Content).Cast<Match>();
    var Projects = matches.Select(x => x.Groups[2].Value).ToList();
    for (int i = 0; i < Projects.Count; ++i)
    {
        if (!Path.IsPathRooted(Projects[i]))
            Projects[i] = Path.Combine(Path.GetDirectoryName(SlnPath),
                Projects[i]);
        Projects[i] = Path.GetFullPath(Projects[i]);
    }

Edit: Amended the regex to include the ".*" as per the comment by Kumar Vaibhav

You can use the EnvDTE.Solution.Projects object to programmatically get access to the projects in a solution.

One gotcha though is that if you have any SolutionFolders in your solution, any projects in these folders are not shown in the above collection.

I've written an article including a code sample on how to get all projects regardless of any solutionfolders

Currently you can use Package Manager Console in VS to obtain that info. Use powershell Get-Project command

Get-Project -All

The trick is to choose the right MsBuild.dll. Under VS2017 it is indeed "C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\15.0\Bin\amd64\Microsoft.Build.dll" (Dont use the standard Msbuild ddl in references. Browse to this path)

c#:

var solutionFile =    
SolutionFile.Parse(@"c:\NuGetApp1\NuGetApp1.sln");//your solution full path name
var projectsInSolution = solutionFile.ProjectsInOrder;
foreach(var project in projectsInSolution)
{
   switch (project.ProjectType)
   {
      case SolutionProjectType.KnownToBeMSBuildFormat:
     {
         break;
     }
     case SolutionProjectType.SolutionFolder:
     {
         break;
     }
  }
}

powershell:

Add-Type -Path (${env:ProgramFiles(x86)} + '\Microsoft Visual 
Studio\2017\Professional\MSBuild\15.0\Bin\amd64\Microsoft.Build.dll')

$slnPath = 'c:\NuGetApp1\NuGetApp1.sln'
$slnFile = [Microsoft.Build.Construction.SolutionFile]::Parse($slnPath)
$pjcts = $slnFile.ProjectsInOrder

foreach ($item in $pjcts)
{

    switch($item.ProjectType)
    {
        'KnownToBeMSBuildFormat'{Write-Host Project  : $item.ProjectName}
        'SolutionFolder'{Write-Host Solution Folder : $item.ProjectName}
    }
}