Check if string starts with letter/character.

Question

_{Wednesday, September 16, 2015 7:34 PM}

Hey Guys,

Working on a user input piece, and I need to validate that the first character in the string is a letter.  I've been dinking around with -

$inputbox = [Microsoft.VisualBasic.Interaction]::InputBox("Please enter your Site location:", "Test Script") 


if(!($inputbox.StartsWith("[a-z]^[A-Z]")){

do{
$inputbox = [Microsoft.VisualBasic.Interaction]::InputBox("Your site location should start with a letter and be $len characters long.  Please enter your Site location:", "Test Script") 
}while(!($inputbox.StartsWith("[a-z]^[A-Z]"))
}

I feel like what I have above will only check if it starts with a.  I could do something like this as well but not sure -

($inputbox[0] -notmatch "[a-z]^[A-Z]")

I could create an alphabet array and loop through that against [0] as well? Any other elegant ways to handle this?  Thanks :)

Ryan

All replies (5)

_{Wednesday, September 16, 2015 7:48 PM ✅Answered | 4 votes}

No need fo r striners just match

$inputbox -match '^[a-zA-Z]'

You can also use the masked text control to do this with a pattern.

You also cannot put the comma in the range or it will also be matched.  Only the dash is allowd hear. A list is just a list [abcdxyz]

\(ツ)_/

_{Wednesday, September 16, 2015 7:43 PM}

Hello,

Regex in powershell is case insensitive by default so you can match it like this:

$test = 'Testvalue'
$test[0] -match "[a-z]"

SingleHop: A leader in Managed Azure

_{Wednesday, September 16, 2015 7:46 PM}

Hi Ryan,

try like the following:

"0T1".Substring(0,1) -match "[a-z,A-Z]"


$inputbox.Substring(0,1) -match "[a-z,A-Z]"

Greetings,

David das Neves

Technology Specialist - Consulting Services
Computacenter AG & Co. oHG - München

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Caution: This post may contain errors.

_{Wednesday, September 16, 2015 8:11 PM}

Here is a very basic example of a masked textbox input dialog

function Call-Test-MaskedEdit{
    [void][reflection.assembly]::Load('System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089')
    
    [System.Windows.Forms.Application]::EnableVisualStyles()
    $form1 = New-Object 'System.Windows.Forms.Form'
    $labelEnterUpTo8Aplhanumer = New-Object 'System.Windows.Forms.Label'
    $buttonCancel = New-Object 'System.Windows.Forms.Button'
    $maskedtextbox1 = New-Object 'System.Windows.Forms.MaskedTextBox'
    $buttonOK = New-Object 'System.Windows.Forms.Button'
    $InitialFormWindowState = New-Object 'System.Windows.Forms.FormWindowState'
    
    $Form_StateCorrection_Load ={$form1.WindowState = $InitialFormWindowState}
    
    $form1.SuspendLayout()
    $form1.Controls.Add($labelEnterUpTo8Aplhanumer)
    $form1.Controls.Add($buttonCancel)
    $form1.Controls.Add($maskedtextbox1)
    $form1.Controls.Add($buttonOK)
    $form1.AcceptButton = $buttonOK
    $form1.ClientSize = '284, 127'
    $form1.FormBorderStyle = 'FixedDialog'
    $form1.MaximizeBox = $False
    $form1.MinimizeBox = $False
    $form1.Name = 'form1'
    $form1.StartPosition = 'CenterScreen'
    $form1.Text = 'Form'
    
    $labelEnterUpTo8Aplhanumer.Font = 'Microsoft Sans Serif, 9.75pt, style=Bold, Italic'
    $labelEnterUpTo8Aplhanumer.Location = '21, 9'
    $labelEnterUpTo8Aplhanumer.Name = 'labelEnterUpTo8Aplhanumer'
    $labelEnterUpTo8Aplhanumer.Size = '240, 38'
    $labelEnterUpTo8Aplhanumer.TabIndex = -1
    $labelEnterUpTo8Aplhanumer.Text = 'Enter up to 8 aplha-numeris and must begin with a letter.
'
    $labelEnterUpTo8Aplhanumer.TextAlign = 'MiddleCenter'
    
    # buttonCancel
    $buttonCancel.DialogResult = 'Cancel'
    $buttonCancel.Location = '173, 92'
    $buttonCancel.Name = 'buttonCancel'
    $buttonCancel.Size = '75, 23'
    $buttonCancel.TabIndex = -1
    $buttonCancel.Text = 'Cancel'
    $buttonCancel.UseVisualStyleBackColor = $True
    
    # maskedtextbox1
    $maskedtextbox1.Location = '99, 50'
    $maskedtextbox1.Mask = 'Laaaaaaa'
    $maskedtextbox1.Name = 'maskedtextbox1'
    $maskedtextbox1.Size = '74, 20'
    $maskedtextbox1.TabIndex = 1
    
    # buttonOK
    $buttonOK.Anchor = 'Bottom, Right'
    $buttonOK.DialogResult = 'OK'
    $buttonOK.Location = '32, 92'
    $buttonOK.Name = 'buttonOK'
    $buttonOK.Size = '75, 23'
    $buttonOK.TabIndex = -1
    $buttonOK.Text = '&OK'
    $buttonOK.UseVisualStyleBackColor = $True
    $form1.ResumeLayout()
    $InitialFormWindowState = $form1.WindowState
    $form1.add_Load($Form_StateCorrection_Load)
    return $form1.ShowDialog()
    
}

Call-Test-MaskedEdit

\(ツ)_/

_{Thursday, September 17, 2015 3:22 PM}

Thanks for your responses, sorry I got caught up yesterday afternoon.  I'll give it a shot today in my script.