Increments the last digit of the nuget version number for a given .csproj file. Intended for the VS2017 project file format and newer.

incrementNugetPackageBuildNumber.ps1

param(
    [parameter(Mandatory=$True)]
    [string] $csprojFile
)
# to invoke from visual studio as a post-build event:
# C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -Command incrementNugetPackageBuildNumber.ps1 -csprojFile "$(ProjectPath)"; 
$projXml = new-object xml
$projXml.Load($csprojFile)

[string]$versionNumberString = $projXml.Project.PropertyGroup.Version

[string[]]$versionNumberComponents = $versionNumberString.Split('.')

$buildNumberString = $versionNumberComponents[$versionNumberComponents.Length-1]
[int]$buildNumber = [System.Int32]::Parse($buildNumberString)

$versionNumberComponents[$versionNumberComponents.Length-1] = ($buildNumber++)

[string]$incrementedVersionNumber = ""

for ($i = 0; $i -lt ($versionNumberComponents.Length); $i++) {
    $component = $versionNumberComponents[$i]
    Write-Output $component    
    if ($i -ne ($versionNumberComponents.Length-1)) {
        $incrementedVersionNumber = $incrementedVersionNumber + "$component"
        $incrementedVersionNumber = $incrementedVersionNumber + "."
    } else { #at the last index
        $incrementedVersionNumber = $incrementedVersionNumber + "$buildNumber"
    }
}

$projXml.Project.PropertyGroup.Version = $incrementedVersionNumber

$projXml.Save($csprojFile)

Write-Host "New version number: $incrementedVersionNumber"