how-to-validate-an-argument-count.md

description	How to Validate an Argument Count
ms.date	09/13/2016
title	How to Validate an Argument Count

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.

Note

For more information about the class that defines this attribute, see System.Management.Automation.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.

  [ValidateCount(1, 3)]
  [Parameter(Position = 0, Mandatory = true)]
  public string[] UserNames
  {
    get { return userNames; }
    set { userNames = value; }
  }
  
  private string[] userNames;

For more information about how to declare this attribute, see ValidateCount Attribute Declaration.

See Also

ValidateCount Attribute Declaration

Writing a Windows PowerShell Cmdlet