Hi All,

 

I think I am overlooking a very simple thing but I cannot figure it out.

I am using a function with a parameter but I want to check if the parameter is valid so there are three valid parameters, test1, test2, and test3 if something else is given as parameter an error is thrown. How can it be that even when I call the function with a valid parameter still the exeption is thrown?

If (($Location -ne "test1" -or ($location -ne "test2" -or ($location -ne "test3"){throw "Location must be test1, test2 or test3)"}

 

Can somebody help?

 

Regards,

Martijn

That is because it cant be all three it will fail always (one of the -or conditions will fail.)

A better options would be test for -eq. I don't generally like to have an if statement with only an else, but in this case it fits

if(($location -eq "test1") -or ($location -eq "test2") -or ($location -eq "test3")){continue}else{throw "Location must be test1, test2 or test3)"}

You could also use a switch statement
switch($location)
{
"test1" {continue}
"test2" {continue}
"test3" {continue}
default {throw "Location must be test1, test2 or test3)"}
}

I prefer using Switch as well. Otherwise, use -and instead of -or. What is happening to expand on Brandon's point is that if $location equals "test1", then the other two comparisons will false and the -OR says, return TRUE if at least one of the comparisons is TRUE which is happening.

I don't believe you can use -and for this. Using -and all conditions must be $true.

-Or will work, but you have to test for a positive response not negative.

The key is understanding the if statement only sees $true or $false. If the result is $true then the if statement completes. If it is $false, the else statement (if exist) completes.

In this case we are checking for -ne. Since $location cannot be all three one of the -ne will return $true.

If we check for -eq instead then it will only return $true if the value matches so we get an expected response.

All that said... switch is clear and the way to go IMO.

But of course. That's what I get for trying to post something without thinking clearly after a long day. There's a reason double negatives are a no-no in writing and they should be in scripting as well. :-)

I agree that using Switch is the way to go. That was my initial thought but I figured I'd try to explain why -or wasn't working. Now that my head is back on straight I think I'll be ok.