如何在循环中验证用户输入？

Question

我是一名学生，我需要在 Powershell ISE 中编写一个脚本，该脚本将为用户提供一个菜单，然后根据他们的选择显示操作系统信息，或者如果他们输入“q”则退出

我已经让菜单输入/输出循环正常工作，但我还需要确保他们选择了有效的选项，如果没有则重新提示。

无论用户输入的值是什么，它都会输出无效消息。

所以如果用户输入 1 就会返回：

输入无效，请从菜单中选择一个选项 @{OsName=Microsoft Windows Server 2016 标准版} 按 Enter 继续...：

我没有编程背景，所以我对 powershell 和编码的理解非常基础，大多数搜索结果都提供了超出我知识范围的示例！

function sysInfoMenu {

    param (
    [string] $Title = 'System Information'
    )

    Clear-Host

    Write-Host "=============== $Title ==============="
    "`n`n"
    Write-Host "Please select from the following options:"
    "`n"
    Write-Host "Press 1 for: OS System"
    Write-Host "Press 2 for: OS Type"
    Write-Host "Press 3 for: OS Architecture (32 or 64 bit)"
    Write-Host "Press 4 for: OS Version"
    Write-Host "Press 5 for: OS Bios Version"
    Write-Host "Press 6 for: Computer Brand"
    Write-Host "Press 7 for: Computer Name"
    Write-Host "Press 8 for: Current Domain"
    Write-Host "Press 9 for: Computer Model"
    Write-Host "Press 10 for: Current User"
    Write-Host "Press 11 for: Timezone"
    Write-Host "Press 'q' to quit."
}

do {
    sysInfoMenu
    $info = $null
    $UserInput = Read-Host "Please select an option from the menu"

        
    switch ($UserInput)
    {
      '1' {$info = Get-ComputerInfo -Property OSName}
      '2' {$info = Get-ComputerInfo -Property OSType}
      '3' {$info = Get-ComputerInfo -Property OSArchitecture}
      '4' {$info = Get-ComputerInfo -Property OSVersion}
      '5' {$info = Get-ComputerInfo -Property BiosVersion}
      '6' {$info = Get-ComputerInfo -Property CsManufacturer}
      '7' {$info = Get-ComputerInfo -Property CsName}
      '8' {$info = Get-ComputerInfo -Property CsDomain}
      '9' {$info = Get-ComputerInfo -Property CsModel}
      '10' {$info = Get-ComputerInfo -Property CsUserName}
      '11' {$info = Get-ComputerInfo -Property TimeZone}
    } 
          
          
       if ($UserInput -lt 1 -gt 11 -ne 'q'){
       Write-Host "Invalid input, please select an option from the menu"
       } 
      
  Write-Host $info
  pause
       
        
}
until ($UserInput -eq 'q') 

Answer 1

你有几个结构性问题。

• 你没有终止你的函数。
• 你没有调用你的函数。
• 您一直调用 Get-ComputerInfo，速度很慢，只需执行一次。
• 您的菜单需要在您的循环中，以便您可以清除屏幕并摆脱以前的答案和/或错误消息。

这里有一些替代代码，我已对其进行评论以帮助您学习。

function SysInfoMenu {

    param (
     [Parameter(Mandatory=$False)]
      [string] $Title = 'System Information'
    )

#Setup:

   $ByeBye   = $False           #Set initial value.
   #Hide the Progress Bar. Remove line if not wanted.
   $ProgressPreference = "SilentlyContinue"
   $CompInfo = Get-ComputerInfo #You only need to call once.

#Main Function Code:

do {
    Clear-Host

    Write-Host "=============== $Title ==============="
    "`n`n"
    Write-Host "Please select from the following options:"
    "`n"
    Write-Host "Press  1 for: OS System"
    Write-Host "Press  2 for: OS Type"
    Write-Host "Press  3 for: OS Architecture (32 or 64 bit)"
    Write-Host "Press  4 for: OS Version"
    Write-Host "Press  5 for: OS Bios Version"
    Write-Host "Press  6 for: Computer Brand"
    Write-Host "Press  7 for: Computer Name"
    Write-Host "Press  8 for: Current Domain"
    Write-Host "Press  9 for: Computer Model"
    Write-Host "Press 10 for: Current User"
    Write-Host "Press 11 for: Timezone"
    Write-Host "Press 'q' to quit."

    $UserInput = Read-Host "Please select an option from the menu"
        
 #Note: use of Break to leave switch once match is found.
       
    switch ($UserInput) {
       '1' {$CompInfo.OSName         ;Break}
       '2' {$CompInfo.OSType         ;Break}
       '3' {$CompInfo.OSArchitecture ;Break}
       '4' {$CompInfo.OSVersion      ;Break}
       '5' {$CompInfo.BiosVersion    ;Break}
       '6' {$CompInfo.CsManufacturer ;Break}
       '7' {$CompInfo.CsName         ;Break}
       '8' {$CompInfo.CsDomain       ;Break}
       '9' {$CompInfo.CsModel        ;Break}
      '10' {$CompInfo.CsUserName     ;Break}
      '11' {$CompInfo.TimeZone       ;Break}
      'q'  {$ByeBye = $True          ;Break}
      default {"Invalid input, please select an option from the menu"}
    } #End Switch      
          
    if (-not $ByeBye) { pause }
        
  } until ($ByeBye) #Exit via $ByeBye value!

} #End Function SysInfoMenu

SysInfoMenu #Call your function

Answer 2

您的脚本几乎没问题，只是您的if 条件有些问题：

$UserInput -lt 1 -gt 11 -ne 'q'

这就是 PowerShell 评估语句的方式，以及为什么它总是进入 if 条件。使用单词 test 作为$userInput:

'test' -lt 1   # => $false
$false -gt 11  # => $false
$false -ne 'q' # => $true

应该是这个样子，注意-and的用法：

'test' -lt 1 -and 'test' -gt 11 -and 'test' -ne 'q'

您可以使用-notmatch 运算符的替代方法，它允许使用Regular Expressions。

在下面的示例中，$UserInput -notmatch $regex 将在任何用户输入不是我们在$validoptions 数组中看到的输入时返回$true（从1 到11 + q)。

$validoptions = 1..11 + 'q'
$regex = '^{0}$' -f ($validoptions -join '$|^')
# Regex: ^1$|^2$|^3$|^4$|^5$|^6$|^7$|^8$|^9$|^10$|^11$|^q$

$waitForUSer = {
    'Press ENTER to Continue...'
    Read-Host
}

do
{
    sysInfoMenu
    $UserInput = Read-Host "Please select an option from the menu"
    
    if ($UserInput -notmatch $regex){
        Write-Warning "Invalid input, please select an option from the menu"
        & $waitForUSer
        continue # => Go to Until, skip next lines
    }

    if($UserInput -eq 'q'){
        continue # => Go to Until and end the loop
    }
   
    $info = switch ($UserInput)
    {
      '1'  { 'Option 1' }
      '2'  { 'Option 2' }
      '3'  { 'Option 3' }
      '4'  { 'Option 4' }
      '5'  { 'Option 5' }
      '6'  { 'Option 6' }
      '7'  { 'Option 7' }
      '8'  { 'Option 8' }
      '9'  { 'Option 9' }
      '10' { 'Option 10' }
      '11' { 'Option 11' }
    }
      
    $info # => Show selection
    & $waitForUSer
}
until ($UserInput -eq 'q')