Poweshell Script GUI selections are appending strings instead of new entries in the array-CodePudding

I have a GUI in my .ps1, and I declared what I think of as an arraylist, $choice = @() to store selected options. Whenever you select anything in the GUI, it adds "Option [#]" to the list. The first time, it does it correctly. each entry you select makes a new line. however, if you deselect one, and reselect it, it appends the string. so instead of the list being:

$choice = (
Option 1
Option 3
)

It is now

$choice= (
Option 1Option 3
)

Here is the full script.

# Set the initial choices
$choice = @()

# Use a while loop to keep the menu open until the user selects the "Exit" option
while ($true) {
    # Clear the screen
    Clear-Host

    # Use a foreach loop to display each menu option, including an asterisk on the selected options
    foreach ($option in "Option 1", "Option 2", "Option 3", "Option 0", "Exit") {
        if ($choice -contains $option) {
            Write-Host "$option *"
        } elseif ($option -eq "Option 0") {
            # "Option 0" is not a selectable option, so always display it as deselected
            Write-Host $option
        } else {
            Write-Host $option
        }
    }

    # Prompt the user to enter their selection
    $userInput = Read-Host "Enter your selection"

    # Use a switch statement to execute the selected options
    switch -regex ($userInput)
    {
        "0" {
            # Code for Option 0
            # Print the selected options and exit the script
            Write-Warning "Choices variable: $choice"
            Write-Host "Selected options: "
            switch ($choice) {
                "Option 1" { 
                    Write-Host "1"
                }
                "Option 2" {
                    Write-Host "2"
                }
                "Option 3" {
                    Write-Host "3"
                }
                default {
                    Write-Host "No selected options."
                }
            }
            # Return to exit the current iteration of the while loop
            return
        }
        "1" {
            # Code for Option 1
            # Check if the user has already selected this option
            if ($choice -contains "Option 1") {
                # Remove the option from the $choice variable
                $choice = $choice | Where-Object {$_ -ne "Option 1"}
            } else {
                # Add the option to the $choice variable
                $choice  = "Option 1"
            }
        }
        "2" {
            # Code for Option 2
            # Check if the user has already selected this option
            if ($choice -contains "Option 2") {
                # Remove the option from the $choice variable
                $choice = $choice | Where-Object {$_ -ne "Option 2"}
            } else {
                # Add the option to the $choice variable
                $choice  = "Option 2"
            }
        }
        "3" {
            # Code for Option 3
            # Check if the user has already selected this option
            if ($choice -contains "Option 3") {
                # Remove the option from the $choice variable
                $choice = $choice | Where-Object {$_ -ne "Option 3"}
            } else {
                # Add the option to the $choice variable
                $choice  = "Option 3"
            }
        }
        "4" {
            # Code for Exit
            # Break out of the while loop to end the script
            break
        }
        default {
            
        # Code for invalid selection or deselection
        # Check if the user has deselected an option
        if ($choice -contains $userInput) {
            # Remove the option from the $choice variable
            $choice = $choice | Where-Object {$_ -ne $userInput}
        }   else {
                # The user has entered an invalid selection
                Write-Host "Invalid selection"
            }
        }
    }
}

I for the life of me can't figure out why removing something from the list breaks the ability to add new items to the list.

CodePudding user response：

Continuing from my comment.

If you are trying to add/remove from a list, then you should avoid using this: $choice = @(). Instead, use $arrlist = New-Object -TypeName System.Collections.ArrayList, and instead of =, use $arrlist.Add("SomeValue") and $arrlist.Remove("SomeValue").

Example:

$arrlist = New-Object -TypeName System.Collections.ArrayList

$arrlist.Add("One")
$arrlist.Add("Two")

$arrlist
# Results
<#
0
1
One
Two
#>

$arrlist.Add("Three")
# Results
<#
2
#>

$arrlist
# Results
<#
One
Two
Three
#>

$arrlist.Remove("Two")

$arrlist
# Results
<#
One
Three
#>

So, a refactor of your code might look like this:

$choice = New-Object -TypeName System.Collections.ArrayList

while ($true) 
{
    Clear-Host

    foreach ($option in 'Option 1', 'Option 2', 'Option 3', 'Option 0', 'Exit') 
    {
        if ($choice -contains $option) 
        {"$option *"} 
        elseif ($option -eq 'Option 0') 
        {$option} 
        else {$option}
    }

    # Prompt the user to enter their selection
    $userInput = Read-Host 'Enter your selection'

    # Use a switch statement to execute the selected options
    switch -regex ($userInput)
    {
        '0' 
        {
            Write-Warning -Message 'Choices variable: $choice'
            'Selected options: '
            switch ($choice) {
                'Option 1' {'1'}
                'Option 2' {'2'}
                'Option 3' {'3'}
                default {'No selected options.'}
            }

            return
        }
        '1' {
            if ($choice -contains 'Option 1') 
            {
                $choice = $choice | 
                Where-Object {$PSItem -ne 'Option 1'}
            } 
            else {$choice.Add('Option 1')}
        }
        '2' 
        {
            if ($choice -contains 'Option 2') 
            {
                $choice = $choice | 
                Where-Object {$PSItem -ne 'Option 2'}
            } 
            else {$choice.Add('Option 2')}
        }
        '3' 
        {
            if ($choice -contains 'Option 3') 
            {
                $choice = $choice | 
                Where-Object {$PSItem -ne 'Option 3'}
            } 
            else {$choice.Remove('Option 3')}
        }
        '4' {break}
        default 
        {            
            if ($choice -contains $userInput) 
            {
                $choice = $choice | 
                Where-Object {$PSItem -ne $userInput}
            }   
            else {Write-Warning -Message 'Invalid selection'}
        }
    }
}