PowerShell Variables and Object Properties in a Double-Quoted String

It’s useful to know how to use PowerShell variables and object properties in a double-quoted string as part of PowerShell’s string expansion.

As a simple example we cab expand the $name variable inside the $sentence variable like so:

$name = "John"
$sentence = "My name is $name"
write-host $sentence
#output
#My name is John

This is easy enough to grasp. Note that PowerShell expansion does NOT work inside single quotes like so:

$name = "John"
$sentence = 'My name is $name'
write-host $sentence
#output
#My name is $name

We can use PowerShell expansion to write the PowerShell version to a variable and output it in a similar way like so:

$version = $PSVersionTable.PSVersion
$sentence = "Powershell version is $version"
write-host $sentence
#output 
#Powershell version is 5.1.19041.1682

However, if we wanted to inject the PowerShell version directly we can see that the following does not work:

$sentence = "Powershell version is $PSVersionTable.PSVersion"
write-host $sentence
#output
#Powershell version is System.Collections.Hashtable.PSVersion

Instead, what we need to do when expanding object properties in PowerShell is to enclose it in $() like so:

$sentence = "Powershell version is $($PSVersionTable.PSVersion)"
write-host $sentence
#output
#Powershell version is 5.1.19041.1682

A final alternative is to use the string format ( -f ) operator like so – here we use placeholders for variable names such as {0} {1} and {2} and after the -f parameter we specify a comma-delimited array of values to substitute in:

$sentence = "Powershell version is {0}" -f $PSVersionTable.PSVersion
write-host $sentence
#output
#Powershell version is 5.1.19041.1682

A slightly more complex version might be:

$sentence = "Powershell major version is {0} and minor version is {1}" -f $PSVersionTable.PSVersion.Major, $PSVersionTable.PSVersion.Minor
write-host $sentence
#output
#Powershell major version is 5 and minor version is 1