Demo-Variable

1.0.1

Demo-Variable.ps1

                                
<#PSScriptInfo

.VERSION 1.0.1

.GUID 06faab35-4c21-4982-97eb-67621775b9ed

.AUTHOR Frits van Drie (3-Link.nl)

.COMPANYNAME 3-Link Opleidingen

.COPYRIGHT free to use and distribute without modifications

.TAGS

.LICENSEURI

.PROJECTURI

.ICONURI

.EXTERNALMODULEDEPENDENCIES 

.REQUIREDSCRIPTS

.EXTERNALSCRIPTDEPENDENCIES

.RELEASENOTES

.PRIVATEDATA

#>

<# 

.DESCRIPTION 

 Developed by 3-Link Opleidingen for training purposes only 

#> 

Param()

# Filename: Demo-Variable.ps1

# Date:     2022-04-13

# Author:   Frits van Drie (3-Link)

Get-Command -Noun "Variable"

New-Variable    -Name DemoVar

Remove-Variable -Name DemoVar -ErrorAction SilentlyContinue

Set-Variable    -Name DemoVar -Value "demo"

Get-Variable    -Name DemoVar

Get-Variable DemoVar

Get-Variable DemoVar -ValueOnly

$DemoVar

# User-created variables:

# Automatic variables   :    Help about_Automatic_Variables  -ShowWindow

# Preference variables  :    Help about_Preference_Variables -ShowWindow

#region: Data types

    ("abc"   ).GetType()      # String

    ('abc'   ).GetType()      # String

    (123     ).GetType()      # Int32

    ("123"   ).GetType()      # String

    (123.6   ).GetType()      # Double

    (Get-Date).GetType()      # DateTime

    ($true   ).GetType()      # Boolean

    @(1,2,3  ).GetType()      # Array

    ( [string]123 ).GetType()

    ('FD00:0:0:5::CAFE').GetType()

    [ipaddress]$b = 'FD00:0:0:5::CAFE'  # type accelerator

    [ipaddress]$c = 'FE80::0:0:5:CAFE'  # type accelerator

    $b.GetType()

    $b | gm

    $b.IsIPv6LinkLocal

    $c.IsIPv6LinkLocal

    ([psobject].Assembly.GetType("System.Management.Automation.TypeAccelerators"))::Get | 

        Select -ExpandProperty keys| Sort | ogv

    # PowerShell uses the [System.Math] library, which consists of many mathematical functions and methods

    [System.Math] | Get-Member -Static -MemberType All

    # Int16     : 2^15 = (-32,768 <=> +32,767)

        [math]::pow(2,15)

    # Int/Int32 : 2^31 = (-2,147,483,648 <=> +2,147,483,647)

        [math]::pow(2,31)

    # Int64     : 2^63 = (-9,223,372,036,854,775,808 <=> +9,223,372,036,854,775,807)

        [math]::pow(2,63)

#endregion: Data types

#region: String and Integer

    $DemoVar = "abc"

    $DemoVar |gm

    $demovar.GetType().Name

    Remove-Variable svc -ea SilentlyContinue

    $Svc = Get-Service sp*

    $Svc | Get-Member

    $Svc.DisplayName

    $svc.GetType()

    Remove-Variable s

    $s = "Spooler"

    $s | Get-Member

    $s.GetType()

    Remove-Variable i

    $i = 25

    $i | Get-Member

    $i.GetType()

    $i = $i+12

    $i.GetType()

    $i

    $i = "25"

    $i.GetType()

    $i = $i+12

    $i.GetType()

    $i

    $i = $i-2500

    $i

    $i.GetType()

    $i = 25

    $i.GetType()

    $i = $i+"12"

    $i.GetType()

    $i

    $i = $i-2500

    $i

    $i.GetType()

    $i = "25"

    $i.GetType()

    Remove-Variable n -ErrorAction SilentlyContinue

    $n = $i

    $n.GetType()

    Remove-Variable m

    $m = $i -as [int32]

    [int32]$m = $i

    $m.GetType()

    $m

    Remove-Variable s

    $s = 25

    $s.GetType()

    $s

    Remove-Variable t

    $s = $s*4

    $t = $s -as [string]

    $t*4

    "="*100

    $t.GetType()

    $t - 5

    $t.GetType()

    $t

    # !!!! Method used to evaluate statements is determined by leftmost object !!!!

    Remove-Variable a

    Remove-Variable b

    $a = "file"

    $b = 3

    ($a*$b) -eq ($b*$a) # Cannot convert value "file" to type "System.Int32"

    ($a*$b)             # filefilefile

    ($b*$a)             # Cannot convert value "file" to type "System.Int32"

    "file" * 3          # leftmost is string: filefilefile

    3 * "file"          # leftmost is int32:  Cannot convert value "file" to type "System.Int32"

    Remove-Variable u

    $u = "abc"

    $u.GetType()

    $u -5

    $u.GetType()

    Remove-Variable s

    $s = '25'

    $s = $s/3

    $s

    $s.GetType()

    [string]$s = 25  # strongtyping

    $s+5

    $s = $s/3

    $s

    $s.GetType()

    $s = '25' 

    $s+5

    [string]$s = $s/3 # strongtyping

    $s

    $s.GetType()

    # ==========================================

    $txt = "Demo"

    "Tekst is $txt"

    'Tekst is $txt'

    'Tekst van $txt is $txt'

    # 'Tekst van $txt is' $txt

    'Tekst van $txt is '+ $txt

    Write-Host 'Tekst van $txt is' $txt -BackgroundColor Yellow -ForegroundColor Red

    "Tekst van `$txt is $txt"  # Backtick `

    $svc = Get-Service Spooler

    $svcName = $svc.name

    "Servicename is $svcName"

    "Servicename is $svc.Name"

    "Servicename is $($svc.Name)"

    "Servicename is " + $svc.Name

    "Service {0} is {1}" -f $svc.Name, $svc.Status

    Remove-Variable logFile -ErrorAction SilentlyContinue

    $logFile = 'C:\LogFile.ps1'

    $logFile | gm

    # identify whether $logFile contains the text C:

    $logFile.Contains("C:") 

    $logFile.Replace("C:","D:") 

    # insert the text \MyScript at character 7

    $logFile.Insert(2,"\MyScript") 

    # that the value stored in $logFile has not changed

    $logFile 

    # update the value of $logFile

    $logFile=$logFile.Insert(2,"\MyScript") 

    $logFile

#endregion:

#region: Date

    $date1 = Get-Date

    $date1

    $date1 | Get-Member

    $date1.Day

    $date1.ToShortDateString()

    $date1.ToShortTimeString()

    $date1.AddDays(3)

    $date1.AddDays(-3)

    Get-Date -Format 'yyyy-MM-dd'

    (Get-Date).ToUniversalTime()

    Get-Date -Format 'HH:mm'

#endregion:

#region: Array

    Remove-Variable arr

    $arr = "aaa", "bbb", "ccc", "ddd","aaa", "bbb", "ccc", "ddd"

    $arr.GetType()

    $arr.length

    $arr[0]

    $arr[3]

    $arr[4]

    $arr[$arr.length -1]

    $arr[-1]

    $arr = $arr + "xxx"

    $arr += "yyy"

    $arr

    # Enumerate the whole array

    for ($i=0; $i -le ($arr.length -1); $i++) {

        $arr[$i]

    }

    Remove-Variable arr

    $arr = "aaa", "bbb", "ccc", "ddd"

    1..10000 | foreach {

        $arr += $_ 

        $arr[-1]

    }

    # !!!

    Remove-Variable arr

    $arr = "xxx", "yyy"

    $arr += "zzz"

    $arr

    $arr.GetType()

    Remove-Variable arr

    [array]$arr = "xxx", "yyy"        # strong typing

    $arr += "zzz"

    $arr

    $arr.GetType()

    Remove-Variable arr

    $arr = @("xxx", "yyy")            # type casting

    $arr += "zzz"

    $arr

    $arr.GetType()

    $arr = @('xxx')

    $arr += 'yyy'

    Remove-Variable arr

    $arr = "line"

    $arr.GetType()

    $arr[0]

    $arr.Length

    Remove-Variable arr2

    $arr2 = "aaa"

    $arr2.GetType()           # String

    $arr2 += "bbbb"

    $arr2

    $arr2.GetType()           # String

    Remove-Variable arr3

    [array]$arr3 = "aaa"      # (strongtyping)

    $arr3.GetType()           # Array

    $arr3 += "bbbb"

    $arr3

    Remove-Variable arr4

    $arr4 = @("aaa","ccc",'dad')

    $arr4.GetType()           # Array

    $arr4 -eq "aaa"           # aaa

    $arr4 -eq "bbb"           # 

    $arr4 -like "*a*"         # aaa, dad

    $arr4 -contains "aaa"     # True

    $arr4 -contains "a"       # False

    $arr4 -contains "bbb"     # False

    # Get-Member

    Remove-Variable arr

    $arr

    $arr.GetType()

    $arr = "aaa",222, 81.4, $true  # String, Int32, Double, Boolean

    $arr.GetType()

    $arr | Get-Member            # Get members of the Items in the Array

    Get-Member -InputObject $arr # Get members of the Array

#endregion

#region: ArrayList

    # ArrayList uses more memoryblocks; preferred when frequently modified

    Remove-Variable arr5

    $arr5 = @()   # prep for filling in loop later

    $arr5.GetType()

    $arr5 += "aaa"

    $arr5 += "bbb"

    $arr5 

    $arr5.length

    $arr5.Count

    $arr5 | Get-Member

    Get-Member -InputObject $arr5

    $arr5 -contains "aaa"

    $arr5.Add("ccc")

    Remove-Variable arrList6

    [System.Collections.arrListayList]$arrList6 = "111","222"  # Dynamic Size

    $arrList6.GetType()

    $arrList6.Add("333")

    $arrList6.Add("444")

    $arrList6

    $arrList6[2]

    $arrList6.Remove("333")

    $arrList6

    Remove-Variable arrList7, arrList8

    $arrList7 = "A", "B"

    $arrList8 = "C", "D"

    $arrList7 = $arrList7 + $arrList8

    $arrList7 += $arrList8

    $arrList7

#endregion:

#region: Dynamic Variable Names

    # Set-Variable -Name "$prf$Letter" -Value (Get-Variable -Name "$prf$Letter" -ValueOnly)

    # Problem: Create variable with dynamic name

    $userName = 'Anna'

    $pass     = 'Pa55w.rd'

    # $passAnna ==> Pa55w.rd

    $"pass$userName" = $pass                           # ERROR

    # Solution 1

    Invoke-Expression "`$pass$userName = '$pass'"

    # Solution 2

    New-Variable -Name "pass$userName" -Value $pass

    $passAnna

    $passwordLength = 12

    $password = $null

    $prf = 'User'

    For($a=1; $a -le 5; $a++) {

        $password = $null

        For($i=1; $i -le $passwordLength; $i++) {

            # Generate a random password (12 characters)

            $number = Get-Random -Minimum 65 -Maximum 90

            $letter = [char]$number

            $password += $letter

        }

        if (Get-Variable -Name "$prf$Letter" -ErrorAction SilentlyContinue){

            $a -= 1

        }

        # Define dynamic variables

        Set-Variable -Name "$prf$Letter" -Value $Password

    }

    Get-Variable -Name "$prf*"

    $prf

    Remove-Variable user*, prf, letter, password, passwordLength, a, i, number

    # =====

    Function Test {

        param ($x)

        New-Variable -Name $("Var$x") -Value "xxxxx"

        $Condition = "(`$Var$x -eq 'xxxxx')"

        if (Invoke-Expression $Condition) {

            Write-Host "$((Get-Variable "Var$x").Name) = $((Get-Variable "Var$x").Value)"

        }

    }

    $str = "ABC"

    Test $str

#endregion:

#region: Variable Scopes

    start 'https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_scopes'

    Function SetName {

        $var = 'Function'

        Write-Host $local:var  -f Cyan

        Write-Host $global:var -f Yellow

    }

    $var = 'Global'

    SetName

    $var

    ###

    Function SetName {

        $global:var = 'Local'

        Write-Host $local:var  -f Cyan

        Write-Host $global:var -f Yellow

    }

    $var = 'Global'

    SetName

    $var

#endregion:

#region: Environment Variables

    $env:USERNAME

    $env:COMPUTERNAME

    Set-Location env:

    dir

    sl C:

    gci env:* -Recurse

#endregion:

#region: Validate value

    # Validate value

    [ipaddress]$ip = Read-Host 'Enter IP address'

    [ValidateRange(0, 10)][int]$n = Read-Host 'Enter a number from 0-10'

    [ValidateSet("ca", "eu", "us")]$region = Read-Host 'Enter countrycode'

#endregion