In the previous tip we illustrated a number of ways how to safely add variables to string content. Adding variables to double-quoted text can expose yet another issue with automatic variable detection. Have a look:
# this is the desired output: # PowerShell Version is 5.1.17763.316 # this DOES NOT WORK: "PowerShell Version is $PSVersionTable.PSVersion"
When you run this code, the output is not what most people would expect. The colorization already hints what it wrong: double-quoted strings expand variables only. They do not care about anything that follows. So since $PSVersionTable is a hash table object, PowerShell outputs the object type name, then adds “.PSVersion” to it:
PS> "PowerShell Version is $PSVersionTable.PSVersion" PowerShell Version is System.Collections.Hashtable.PSVersion
Here are four popular alternatives that work:
# use a subexpression "PowerShell Version is $($PSVersionTable.PSVersion)" # use the format (-f) operator 'PowerShell Version is {0}' -f $PSVersionTable.PSVersion # concatenate (provided the first element is a string) 'PowerShell Version is ' + $PSVersionTable.PSVersion # use simple variables $PSVersion = $PSVersionTable.PSVersion "PowerShell Version is $PSVersion"
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