Operator and its Description
$a = "The quick brown fox jumped over the lazy dog"
$z = "fox"
If ($a -contains $z)
$b = "The line is " + $True
$b = "This is lie and " + $false
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$Users = "John Doe","Dave Davis","Dick Jones"
$Users -contains "John Doe"
The result is True
Examples for comparison operators are -eq, -ne, -ge, -notlike, -gt, -lt, -le, -like, -match, -notmatch, -contains, -notcontains, -is, -isnot, -in, -notin, and so on.
More details Powershell Operators
More details on Array-Hashes