chomp $user_input;
my $regex = eval { qr{$user_input} };
my $error = $@;

unless (defined $regex) {
   print "Your regex seems to be invalid. Try `perldoc perlretut` for 
+an explanation of valid regexes.\n"
   print "Regex compilation error was: $error";
}

[download]

See also: eval, perlop.

Update: unconfused variable names, as pointed out by choroba++ and ReturnOfThelonious++

In reply to Re: Making sure user input is a valid regexp by moritz
in thread Making sure user input is a valid regexp by gri6507

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