PowerShell validation helper functions

Validation_helpers.ps1

function Test-Url([Parameter(ValueFromPipeline)] [string] $url) {
    $url -cmatch '^https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)$'
}

function Test-Guid([Parameter(ValueFromPipeline)] [string] $guid) {
    try { [System.Guid]::Parse($guid) | Out-Null; $true } catch { $false }
}

function Test-IPAddress([Parameter(ValueFromPipeline)] [string] $ip, [switch] $cidr) {
    if ($cidr) { $ip -match '^(?:\d{1,3}\.){3}\d{1,3}/\d\d$' }
    else { try { [System.Net.IPAddress]::Parse($ip) | Out-Null; $true } catch { $false } }
}