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Compare Get-Date to Date as String
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How to parse (French) full month into datetime object in PowerShell?
(1 answer)
Closed 4 years ago.
$Deldate = "19-06-2018"
$Newdate = "04-06-2018"
I need to check which date is bigger.
if ($Deldate -ge $NewDate) {
write-host "NewDate is bigger"
}
else {
write-host "Deldate is bigger"
}
This is not working for me, and it looks like the format is not "System.DateTime". I'm getting the date values are from an external CSV file. How do I find a solution for this?
You should be able to cast the strings that you have created to the "datetime" type like so:
$Deldate = "19-06-2018"
$Newdate = "04-06-2018"
$Deldate = [datetime]::ParseExact("$Deldate", 'dd-MM-yyyy', $null)
$Newdate = [datetime]::ParseExact("$Newdate", 'dd-MM-yyyy', $null)
if ($Deldate -ge $NewDate) {
write-output "NewDate is bigger than or equal to"
}
else {
write-output "Deldate is bigger"
}
This returns the correct result. You can't simply use the Get-Date cmdlet, since the -Date required parameter also requires that the parameter be of type "DateTime", so you first have to cast the strings to the DateTime type.
Originally Proposed...
I am going to change the format of your date just a hair from DD-MM-YYYY to MM-DD-YYYY:
$Deldate = Get-Date "06-19-2018"
$Newdate = Get-Date "06-04-2018"
if ($Deldate -gt $Newdate) {
'Deldate is larger'
}
else {
'Newdate is larger or equal'
}
I'm creating two date objects based on the respective dates you gave. I'm comparing the two objects; PowerShell knows how to do the date math.
It works fine for U.S. style dates.
After much discussion...
However, for non-US style dates, consider calling datetime's constructor:
$Deldate = New-object 'datetime' -ArgumentList 2018, 6, 19, $null, $null, $null
$Newdate = New-object 'datetime' -ArgumentList 2018, 6, 4, $null, $null, $null
if ($Deldate -gt $Newdate) { 'Deldate is larger' } else { 'Newdate is larger or equal' }
Or, as proposed the [datetime]::ParseExact() method; documented here.
PowerShell is good with dates; it just has to know it's a date...
$Deldate = get-date "19-06-2018"
$Newdate = get-date "04-06-2018"
if ($Deldate -ge $NewDate) {
write-host "NewDate is bigger"
}
else {
write-host "Deldate is bigger"
}
Note: You could cast [datetime]$Deldate ="19-06-2018", but as explained in comments to PowerTip: Convert String into DateTime Object, it's valid only for US date format.
Related
I'm trying to validate a textbox in Powershell. It should only allow the format dd.MM.yyyy (f.e 22.11.2022). Yet if I type some random characters (f.e 20.2), I get erros instead of a MessageBox.
I've tried something like this:
if($Starttextbox.Text -as [DateTime] -or $Endtextbox.Text -as [DateTime]){
"do something"
}else{
[System.Windows.MessageBox]::Show('Type in correct format','format','Ok','Error')
}
You could create a small function and use a combination of RegEx and Get-Date commandlet, like below.
$StartDate = '22.12.2022' #Good
$EndDate = '22.19.2022' #Bad
function Get-ValidDate { param($DateToCheck)
$DateToCheck -match '(\d{2})\.(\d{2})\.(\d{4})' | Out-Null
if($matches.count -eq 4) {
$ValidDate = $(Get-Date -Date "$($matches[2])-$($matches[1])-$($matches[3])" -Format 'dd.MM.yyyy') 2>> $NULL
}
if($DateToCheck -eq $ValidDate) {
return "GoodDate"
}
}
if((Get-ValidDate $StartDate) -and (Get-ValidDate $EndDate)) {
Write-Host "These are Good Dates!" # DO STUFF
} else {
Write-Host "These are Bad Dates!" # MESSAGEBOX
}
2>>$NULL will remove your Get-Date error messages as all you're looking for is a valid datetime from Get-Date. Function will only return on RegEx match and a valid date.
Here is the regex for dates in the format of dd.mm.yyyy:
^(?:(?:31(\/|-|\.)(?:0?[13578]|1[02]))\1|(?:(?:29|30)(\/|-|\.)(?:0?[13-9]|1[0-2])\2))(?:(?:1[6-9]|[2-9]\d)?\d{2})$|^(?:29(\/|-|\.)0?2\3(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00))))$|^(?:0?[1-9]|1\d|2[0-8])(\/|-|\.)(?:(?:0?[1-9])|(?:1[0-2]))\4(?:(?:1[6-9]|[2-9]\d)?\d{2})$
I am trying to use "DO...Until" in a script to require a user to enter a date. I want to ensure that the date is valid and that the script is able to use that date. I'm fairly new to PS and I'm not certain what I'm doing wrong. It keeps looping even if I put in a valid date.
Do #Start Get Effective Date#
{
$StartDate = Read-Host ' What is the effective date? Format: MM/DD/YYYY '
if ($StartDate -ge 1)
{ Write-Host " You Entered an Effective date of: $StartDate "
}
else
{ Write-Host " Please enter the effective date " -ForegroundColor:Green }
} Until ($StartDate -ge 1)
#End Get Effective Date#
I'm not certain if I am using the wrong '-ge' or not. Once I am able to get a valid date from the user I want the script to move to the next step.
you were close to ;-)
Do{
[string]$StartDate = Read-Host 'What is the effective date? Format: MM/DD/YYYY'
try {
[datetime]$StartDate = [datetime]::ParseExact($startdate, 'MM/dd/yyyy', [cultureinfo]::InvariantCulture)
}
Catch {
}
}
Until ($StartDate -is [DateTime])
The TryParseExact method seems a good fit for what you're looking to achieve, no need for error handling:
[ref] $date = [datetime]::new(0)
do {
$startdate = Read-Host 'What is the effective date? Format: MM/DD/YYYY'
$parsed = [datetime]::TryParseExact($startdate, 'MM/dd/yyyy', [cultureinfo]::InvariantCulture, [Globalization.DateTimeStyles]::None, $date)
} until($parsed)
$date.Value
To offer a concise alternative that relies on the fact that casting a string to [datetime] in PowerShell by default recognizes date strings such as '12/24/2022' (representing 24 December 2022), irrespective of the current culture, because PowerShell's casts, among other contexts, use the invariant culture:
$prompt = 'What is the effective date? Format: MM/DD/YYYY'
# Keep prompting until a valid date is entered.
while (-not ($startDate = try { [datetime] (Read-Host $prompt) } catch {})) {}
"Date entered: "; $startDate
Note: A [datetime] cast also recognizes other string formats, such as '2022-12-24'
Another option would be to create a PowerShell function and accept the date as a parameter. Functions can use a variety of approaches for parameter validation, including script.
https://learn.microsoft.com/powershell/module/microsoft.powershell.core/about/about_functions_advanced_parameters?view=powershell-7.2
Date Time objects allow us to perform actions like this:
$CurrentDate = Get-Date
$TextDate = get-date -date "02/10/2016"
if ($TextDate -lt $CurrentDate){
Write-Host "True"
}
else {
Write-Host "False"
}
This outputs "True" because $TextDate is less than $CurrentDate.
Following the same logic, why does the following code output false?
$CurrentDate = Get-Date -UFormat %V
$TextDate = Get-Date -date "02/10/2016"
$TextDate = Get-Date -date $TextDate -UFormat %V
if ($TextDate -lt $CurrentDate){
Write-Host "True"
}
else {
Write-Host "False"
}
The only difference is that we are comparing the week of the year. If you change the comparison to -gt, the code returns True.
Formatted dates are strings, not integers. The string "6" is after the string "11".
This would be the most correct way to do this:
First, decide what the "first week of the year" actually means:
$CalendarWeekRule = [System.Globalization.CalendarWeekRule]::FirstDay;
#$CalendarWeekRule = [System.Globalization.CalendarWeekRule]::FirstFourDayWeek;
#$CalendarWeekRule = [System.Globalization.CalendarWeekRule]::FirstFullWeek;
Then, decide which day of the week is the first day of the week:
$FirstDayOfWeek = [System.DayOfWeek]::Sunday;
#$FirstDayOfWeek = [System.DayOfWeek]::Monday;
#Any day is available
Then you can get your correct week number:
$Today = (Get-Date).Date;
$TodayWeek = [cultureinfo]::InvariantCulture.Calendar.GetWeekOfYear($Today, $CalendarWeekRule, $FirstDayOfWeek);
$TargetDate = Get-Date -Date "2016-02-10";
$TargetWeek = [cultureinfo]::InvariantCulture.Calendar.GetWeekOfYear($TargetDate, $CalendarWeekRule, $FirstDayOfWeek);
if ($TargetWeek -lt $TodayWeek) { $true } else { $false }
Note that if you want a full ISO 8601 week, it's somewhat more complicated.
Because you are comparing string-objects.
(Get-Date -UFormat %V).GetType().FullName
System.String
When comparing strings using -gt and -lt it sorts the strings and because 6 comes after 1, your 6 -lt 11-test returns false.
Both $TextDate and $CurrentDate are of type [string] so what you are evaluating is '6' -lt '11' which will return false. Operators are based on the left side type in PowerShell. So in order to force an integer comparison modify your expression as under
if ([int]$TextDate -lt $CurrentDate)
{
Write-Host "True"
}
else
{
Write-Host "False"
}
I am currently trying to convert a date from the one displayed in regedit to a readable datetime format. But I do not know how to do this, I'm working with the following:
.GetValue('InstallDate')
And in the .csv file, it display it as this: 20150914
How would I go about converting that into a readable date?
try
[datetime]::Parseexact("20150914","yyyyMMdd", $null )
I'm not sure why you down voted the other answer because he is right on the money with [Datetime]::ParseExact you will have to deal with the null values though
$Regbase = Get-ChildItem HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\
foreach ($entry in $regBase)
{
$date = (Get-ItemProperty HKLM:\$entry | select installdate).installdate
try
{
[DateTime]::ParseExact($date, "yyyyMMdd", [CultureInfo]::InvariantCulture)
}
catch [exception]
{
"Date Value: $date"
}
}
PowerShell Date is just .NET DateTime. Check DateTime.ParseExact.
[DateTime]::ParseExact("20151010", "yyyyMMdd", [CultureInfo]::InvariantCulture)
I have a requirement where I need to read a date from a CSV file and compare it to a date variable within the script. However, my code doesn't work when some of the date entries in the CSV file are blank. Any idea how I can store a blank date in [datetime] variable?
Here's the part of my code:
#This is my date variable in script
$InactivityDate = (Get-Date).AddDays(-62).Date
Import-Csv $MyCSV | ForEach {
#This is the date variable i'm reading from csv file
$whenCreated = $_.whenCreated
#This converts value in string variable $whenCreated to [DateTime] format
$ConvertWhenCreated = ([datetime]::ParseExact($whenCreated,"dd/MM/yyyy",$null))
#Comparing dates
if($ConvertWhenCreated -le $InactivityDate)
{
"Account is dormant"
}
Above code works fine when $whenCreated contains some value, but when it's blank PowerShell obviously cannot compare a date variable with blank value :(
The only solution I can see now is to check if $whenCreated is blank and save a very old date like it happens in Excel, e.g.:
if($whenCreated -eq "")
{
$whenCreated = "01/01/1900 00:00:00"
}
Should this be OK or is there another logical solution?
Your problem most likely isn't with the comparison, but with the conversion of the blank value to a date via ParseExact(). If you want accounts with no date treated as dormant you could simply do something like this:
$whenCreated = $_.whenCreated
if ($whenCreated) {
$whenCreated = [DateTime]::ParseExact($whenCreated, 'dd/MM/yyyy', $null)
}
if ($whenCreated -le $InactivityDate) {
'Account is dormant'
}
Checking if an empty string (or $null) is lesser or equal to $InactivityDate will return $true as long as $InactivityDate contains a date.
You already test if the string is empty, which is good. But there is no need to assign a fake old date, you can simply assign $null:
$InactivityDate = (Get-Date).AddDays(-62)
$dateString = "2014-11-01"
if ($dateString) {
$date = Get-Date $dateString
} else {
$date = $null
}
if ($date -le $InactivityDate) {
"Account is dormant"
}