Switch handling with global arrays - powershell

Question

Say I have 2 global arrays:
$Global:Values = #(1..100)
$Global:Test = #(75, 50, 25, 101)
Then I create a Switch by piping $Global:Test into a ForEach loop by using different conditions which I tried troubleshooting to get any kind of response:
$Global:Test | ForEach-Object ($_) {
$_
Switch ($_) {
($_ -contains $Global:Values) {Write-Host "Excellent"}
($_ -in $Global:Values) {Write-Host "Satisfactory"}
($_ -eq "25") {Write-Host "Unsatisfactory"}
Default {Write-Host "Invalid Grade"}
}
}
Output:
75
Invalid Grade
50
Invalid Grade
25
Invalid Grade
101
Invalid Grade
All of these switch statements do not work except the default. I don't know what I'm missing, but I'm sure it's a simple mistake I'm overlooking. Can anyone help me spot this mistake?

Answer 1

The foreach() statement is not the same as the ForEach-Object cmdlet, and you seem to be combining the syntax of both.
Additionally, you're using the switch statement incorrectly.
The part you're trying to match against needs to be a value:
switch ($something)
{
5 { "5 thing" }
(10 + 10) { "20 thing" }
}
or a scriptblock expression that returns a truthy or falsey value:
switch ($something)
{
{ $_ -gt 5 } { "do > 5 thing" }
{ Test-SomeCondition -Value $_ } { "do other thing" }
}
So you want the scriptblock form, but you're using parentheses.
So here's the ForEach-Object form:
$Global:Test | ForEach-Object {
Switch ($_) {
{$_ -contains $Global:Values} {Write-Host "Excellent"}
{$_ -in $Global:Values} {Write-Host "Satisfactory"}
"25" {Write-Host "Unsatisfactory"}
Default {Write-Host "Invalid Grade"}
}
}
or the foreach form:
foreach($value in $Global:Test) {
Switch ($value) {
{$_ -contains $Global:Values} {Write-Host "Excellent"}
{$_ -in $Global:Values} {Write-Host "Satisfactory"}
"25" {Write-Host "Unsatisfactory"}
Default {Write-Host "Invalid Grade"}
}
}
Also of note, the switch statement can actually work directly with arrays, so you don't have to iterate first. Basic example:
switch (1..10)
{
{ $_ -gt 5 } { "Second Half"}
default: { "First Half" }
}
So with yours, maybe:
Switch ($Global:Test) {
{$_ -contains $Global:Values} {Write-Host "Excellent"}
{$_ -in $Global:Values} {Write-Host "Satisfactory"}
"25" {Write-Host "Unsatisfactory"}
Default {Write-Host "Invalid Grade"}
}
Small addendum: stop using Global variables!