This article introduces whether the input parameters are legal and can be constrained by regular expressions when customizing PowerShell functions. Regular expressions to constrain input parameters will be used to use the ValidatePattern directive.
Previously, we used ValidateSet as a smart prompt for parameters, but in fact it also checks the compliance of parameter input. Because ValidateSet specifies the range of input parameters and parameters that are not within this range, one cannot prompt intelligently. In addition, even if it is input, it cannot pass the compliance check of the input parameters of the function, so the program cannot continue to execute.
So since ValidateSet checks input parameters in the form of a collection, then if ValidatePattern uses regular expression rules to check the input parameters, Brother Hong believes that you will understand it. Let's take a look at how to use regular expressions to perform compliance checks on input parameters:
function Get-ZIPCode {
param(
[ValidatePattern('^\d{6}$')]
[String]
$ZIP
)
“Here is the ZIP code you entered: $ZIP”
}
The above is a function that checks the input zip code. [ValidatePattern('^\d{6}$')] means using the regular expression '^\d{6}$' to check the compliance of the input parameters. The regular expression "^\d{6}$" is represented by a 6-digit number, which is the format of the zip code.
Therefore, through the ValidatePattern instruction, as long as you understand the regular expression, you can conduct powerful checks on the compliance of the input parameters, thereby greatly improving the security of the function.
Regarding the use of regular expressions to check the input parameters, this article introduces so much. I hope it will be helpful to you. Thank you!