How to Validate an Argument Count
This example shows how to specify a validation rule that the Windows PowerShell runtime can use to check the number of arguments (the count) that a parameter accepts before the cmdlet is run. You set this validation rule by declaring the ValidateCount attribute.
For more information about the class that defines this attribute, see ValidateCountAttribute.
To validate an argument count
Add the Validate attribute as shown in the following code. This example specifies that the parameter will accept one argument or as many as three arguments.
For more information about how to declare this attribute, see ValidateCount Attribute Declaration.