Boolean literals in PowerShell

Question

$true and $false.

Those are constants, though. There are no language-level literals for Booleans.

Depending on where you need them, you can also use anything that coerces to a Boolean value, if the type has to be Boolean, e.g., in method calls that require Boolean (and have no conflicting overload), or conditional statements. Most non-null objects are true, for example. null, empty strings, empty arrays and the number 0 are false.

[bool]1 and [bool]0 also works.

To add more information to already existing answers: The Boolean literals $true and $false also work as is when used as command line parameters for PowerShell scripts. For the below PowerShell script which is stored in a file named installmyapp.ps1:

param (
    [bool]$cleanuprequired
)

echo "Batch file starting execution."

Now if I've to invoke this PowerShell file from a PowerShell command line, this is how I can do it:

installmyapp.ps1 -cleanuprequired $true

OR

installmyapp.ps1 -cleanuprequired 1

Here 1 and $true are equivalent. Also, 0 and $false are equivalent.

Note: Never expect that string literal true can get automatically converted to boolean. For example, if I run the below command:

installmyapp.ps1 -cleanuprequired true

it fails to execute the script with the below error:

Cannot process argument transformation on parameter 'cleanuprequired'. Cannot convert value "System.String" to type "System.Boolean". Boolean parameters accept only Boolean values and numbers, such as $True, $False, 1 or 0.