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On my Machine each one of the following code snippets throws and exception instead of printing to the standard output "1" and "2" Why the exception is not being Caught?

try {
    [int]$a = 1/0
catch {
    write 1
finally {
    write 2
try {
    [int]$a = 1/0
catch [System.Exception] {
    write 1
finally {
    write 2
As you are using constants, the interpreter tries to precompute the result and fails with a division by zero error. Your code does not even get executed so there's nothing to trap.
You can verify this for yourself by changing your code to use variables, forcing it to be executed.
try {
    $divisor = 0
    [int]$a = 1/$divisor
catch {
    write 1
finally {
    write 2
From Windows PowerShell in Action (p.257)
  
The example here uses 1/$null. The reason for doing this instead of
  simply 1/0 is because the PowerShell interpreter does something called
  constant expression folding.
  
It looks at expressions that contain only constant values. When it
  sees one, it evaluates that expression once at compile time so it
  doesn’t have to waste time doing it again at runtime.
  
This means that impossible expressions, such as division by zero, are
  caught and treated as parsing errors. Parsing errors can’t be caught
  and don’t get logged when they’re entered interactively, so they don’t
  make for a good example. (If one script calls another script and that
  script has one of these errors, the calling script can catch it, but
  the script being parsed cannot.)
                So... my bad. :) It was not RuntimeException. I just copied over FullyQualifiedErrorId, and that does not contain detail important for that scenario. Regarding v3: I can't find any reference (yet). Doug Finke mentioned this calculation as example in his upcoming book, "PowerShell for Developers", so I tried and realized that in v3 it actually can be caught. Sorry for any confusion caused by using wrong terminology... :)
– BartekB
                May 16 '12 at 18:29
                Thx for the update. Should you find a reference, I hope you would still post it here.
– Lieven Keersmaekers
                May 18 '12 at 8:13
                OK, not sure why I haven't spotted this sooner... Look up WMF 3.0 Release Notes, Page 13. There is information about this particular case: "Constant folding is not performed during parsing." And later, in Error Message column "No parsing. The error is detected at runtime". Obviously, with that we get possibility to catch this error. You can find Release Notes for WMF 3.0 RC here: microsoft.com/en-us/download/details.aspx?id=29939
– BartekB
                Jun 4 '12 at 14:37
You can try to throw an exception with that kind of line : trap { "Your Exception" } 1/0

This will throw the exception "divide by 0". Though I don't really understand why your code doesn't throw an exception ._.

PS : Isn't that supposed to be catch [System.SystemException] ? :)
        
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