Powershell script for generating a version number and inserting it into the csproj

SetCsProjVersion.ps1

$csprojPath = $args[0] # path to the file i.e. 'C:\Users\ben\Code\csproj powershell\MySmallLibrary.csproj'
$newVersion = $args[1] # the build version, from VSTS build i.e. "1.1.20170323.1"

Write-Host "Starting process of generating new version number for the csproj"

$splitNumber = $newVersion.Split(".")
if( $splitNumber.Count -eq 4 )
{
	$majorNumber = $splitNumber[0]
	$minorNumber = $splitNumber[1]
	$revisionNumber = $splitNumber[3]
	
	# I need to keep my build number under the 65K int limit, hence this hack of a method
	$myBuildNumber = (Get-Date).Year + ((Get-Date).Month * 31) + (Get-Date).Day
	$myBuildNumber = $majorNumber + "." + $minorNumber + "." + $myBuildNumber + "." + $revisionNumber

	$filePath = $csprojPath
	$xml=New-Object XML
	$xml.Load($filePath)
	$versionNode = $xml.Project.PropertyGroup.Version
	if ($versionNode -eq $null) {
		# If you have a new project and have not changed the version number the Version tag may not exist
		$versionNode = $xml.CreateElement("Version")
		$xml.Project.PropertyGroup.AppendChild($versionNode)
		Write-Host "Version XML tag added to the csproj"
	}
	$xml.Project.PropertyGroup.Version = $myBuildNumber
	$xml.Save($filePath)

	Write-Host "Updated csproj "$csprojPath" and set to version "$myBuildNumber
}
else
{
	Write-Host "ERROR: Something was wrong with the build number"
}

$xml.Project.PropertyGroup might require index[0] to avoid set error because there might be several nodes PropertyGroup in your csproj

I use:
$xml.Project.PropertyGroup[0].FileVersion = $newVersion

on my project

God bless you ;)