Unable To Set Application Property Using MSbuild.exe - visual-studio

Question

If I go to Project->MyApp->Properties->Settings and enter Name like WhichApp of type string and enter the Scope as Application and Value of PCB. When I show the value in
my main form using MessageBox.Show(Properties.Settings.Default.WhichApp); I see a message box showing "PCB".
But if I try to set the property using MSBuild.exe -property:WhichApp=SUB when I view the property value I still see "PCB".
How can I call the MSBuild.exe compiler tool to set the property at build time?
I tried used External Tools in Visual Studio..
Title: Set Property
Command: C:\Program Files(x86)\Microsoft Visual Studio\2017\WDExpress\MSBuild\15.0\Bin\MSBuild.exe
Arguments: -property:WhichApp=SUB
Initial Directory: $(ProjectDir)
---- WHAT I'M TRY TO ACCOMPLISH IN LOAD() METHOD OF MAIN FORM ----
if (Properties.Settings.Default.PCAppConfig == "PCB")
{
// create new PCB form
// PCBForm.ShowDialog();
}
else if (Properties.Settings.Default.PCAppConfig == "SUB")
{
// create new SUB form
// SUBForm.ShowDialog();
}
--- In solution by jtijn, I tried this to add another property called VersionNum but fails... ---
<Target Name="BeforeBuild">
<PropertyGroup>
<!--Default value.-->
<PcAppConfig Condition="'$(PcAppConfig)' == ''">PCB</PcAppConfig>
<VersionNum Condition="'$(VersionNum)' == ''">1.0.0.66</VersionNum>
<!--The source code.-->
<TheSourceCode>internal static class PcAppConfig{ public static readonly string value = "$(PcAppConfig)"%3B%0A }internal static class VersionNum{ public static readonly string value = "$(VersionNum)"%3B</TheSourceCode>
</PropertyGroup>
<!--Get current source so we can only create it again when needed, to avoid being recompiled.-->
<ReadLinesFromFile File="PcAppConfig.cs" ContinueOnError="True">
<Output TaskParameter="Lines" ItemName="CurrentSourceCode" />
</ReadLinesFromFile>
<!--Write source, if needed.-->
<WriteLinesToFile File="PcAppConfig.cs" Overwrite="True" Lines="$(TheSourceCode)" Condition="'#(CurrentSourceCode)' != '$(TheSourceCode)'" />
</Target>
--- Doesn't compile when values are changed, Fails to create setup files ...
My arguments to MSBuild.exe
SelectApp.csproj.user /p:PcAppConfig=SUB /p:VersionNum=1.0.0.67
<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="Current" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<ItemGroup>
<Compile Update="Form1.cs">
<SubType>Form</SubType>
</Compile>
</ItemGroup>
<Target Name="BeforeBuild">
<PropertyGroup>
<!--Default value.-->
<PcAppConfig Condition="'$(PcAppConfig)' == ''">PCB</PcAppConfig>
<VersionNum Condition="'$(VersionNum)' == ''">1.0.0.66</VersionNum>
<!--The source code.-->
<TheSourceCode>internal static class PCAppConfig{ public static readonly string value = "$(PcAppConfig)"%3B }%0Ainternal static class VersionNum{ public static readonly string value = "$(VersionNum)"%3B }</TheSourceCode>
</PropertyGroup>
<!--Get current source so we can only create it again when needed, to avoid being recompiled.-->
<ReadLinesFromFile File="PcAppConfig.cs" ContinueOnError="True">
<Output TaskParameter="Lines" ItemName="CurrentSourceCode" />
</ReadLinesFromFile>
<!--Write source, if needed.-->
<WriteLinesToFile File="PcAppConfig.cs" Overwrite="True" Lines="$(TheSourceCode)" Condition="'#(CurrentSourceCode)' != '$(TheSourceCode)'" />
<ItemGroup>
<Compile Update="PcAppConfig.cs">
<SubType>Component</SubType>
</Compile>
</ItemGroup>
</Target>
<Target Name="AfterCompile">
<Exec Command=""$(ProgramFiles)\Microsoft Visual Studio\2019\Professional\Common7\IDE\devenv.com" C:\DummyApps\SelectApp\PCBSetup\PCBSetup.vdproj /build "Debug|AnyCPU""/>
</Target>
</Project>

Answer 1

You can have the project generate C# source code based on an msbuild property. This target goes at the end in the project file:
<Target Name="BeforeBuild">
<PropertyGroup>
<!--Default value.-->
<PcAppConfig Condition="'$(PcAppConfig)' == ''">PCB</PcAppConfig>
<!--The source code.-->
<TheSourceCode>internal static class PcAppConfig{ public static readonly string value = "$(PcAppConfig)"%3B }</TheSourceCode>
</PropertyGroup>
<!--Get current source so we can only create it again when needed, to avoid being recompiled.-->
<ReadLinesFromFile File="PcAppConfig.cs" ContinueOnError="True">
<Output TaskParameter="Lines" ItemName="CurrentSourceCode" />
</ReadLinesFromFile>
<!--Write source, if needed.-->
<WriteLinesToFile File="PcAppConfig.cs" Overwrite="True" Lines="$(TheSourceCode)" Condition="'#(CurrentSourceCode)' != '$(TheSourceCode)'" />
</Target>
The resulting source file needs to be added to your project, can do this in VS after building once or else add this line along with the other Compile items:
<Compile Include="PcAppConfig.cs" />
Now in your code you can just use PcAppConfig.value.
To change the value build like
msbuild my.csproj /p:PcAppConfig=SUB