Calling the value of a variable from a variable value - powershell

Question

I run a script in powershell
./name -i tom
then i want to call the value of a variable called $Tom from the input reference value of $i
$tom = 29
$andrew = 99
$bill = 5
Echo $i's age is $i
This would print:
toms age is 29

Answer 1

In powershell this would look like this:
Contents of name.ps1:
$person = $args
$ages = #{"Tom" = 23;
"Andrew" = 99;
"Bill" = 5}
$age = $ages[$person]
Write-Host "$person's age is $age"
And you would call it like this
.\name.ps1 "tom"
$argscontains all the arguments that you send to the script. So if you call the script like this: .\name.ps1 "tom" "bill", your result would be: tom bill's age is 23 5

Answer 2

I would use hashtable, but if you have global variables, you can use following:
#variables
$tom = 29
$andrew = 99
$bill = 5
#your parameter
$i = "tom"
#echo
Echo "$i's age is $((Get-Variable | ? {$_.Name -eq $i}).Value)"

Answer 3

An alternative approach to those provided. More code, arguably overkill, but I think it's good to get a handle on PowerShell's param feature.
# PowerShell's native argument/parameter support
param(
[string]$name
)
# Create an array with Name and Age properties as hashtable.
$people = #(
#{ Name = "Tom" ; Age = 29},
#{ Name = "Andrew" ; Age = 99},
#{ Name = "Bill" ; Age = 5}
)
# Find the person by comparing the argument to what is in your array
$person = $people | Where-Object {$_.Name -eq $name}
# Single name version: If the person is found, print what you would like. Otherwise let the user know name not found
if($person -ne $null){
Write-Host "$($person.Name) is $($person.Age) years old"
}else{
Write-Host "$name not found in list."
}
<# Multiple name version : get rid of the param section
foreach ($name in $args){
$person = $people | Where-Object {$_.Name -eq $name}
if($person -ne $null){
Write-Host "$($person.Name) is $($person.Age) years old"
}else{
Write-Host "$name not found in list."
}
}
#>