#!/usr/bin/perl use warnings; for my $i (1..5) { $x+1; # here just to throw an error to STDERR print "$i\n"; } __END__ Useless use of addition (+) in void context at C:\Projects_Perl\testing\demoStdErrorTiming1.pl line 6. Name "main::x" used only once: possible typo at C:\Projects_Perl\testing\demoStdErrorTiming1.pl line 6. Use of uninitialized value $x in addition (+) at C:\Projects_Perl\testing\demoStdErrorTiming1.pl line 6. Use of uninitialized value $x in addition (+) at C:\Projects_Perl\testing\demoStdErrorTiming1.pl line 6. Use of uninitialized value $x in addition (+) at C:\Projects_Perl\testing\demoStdErrorTiming1.pl line 6. Use of uninitialized value $x in addition (+) at C:\Projects_Perl\testing\demoStdErrorTiming1.pl line 6. Use of uninitialized value $x in addition (+) at C:\Projects_Perl\testing\demoStdErrorTiming1.pl line 6. 1 2 3 4 5