Functions/Get-DaysSinceToday.ps1

Function Get-DaysSinceToday {
    [CmdletBinding(PositionalBinding=$false)]
Param
    (
        [Parameter(Mandatory=$True)][string]$Year,
        [Parameter(Mandatory=$True)][string]$Month,
        [Parameter(Mandatory=$True)][string]$Day
    )
    (Get-Date).Date.Subtract((New-Object DateTime($Year,$Month,$Day))).Days
}