On Sat, Jan 21, 2017 at 9:39 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Pavan Deolasee <pavan.deolasee@gmail.com> writes: > On Sat, Jan 21, 2017 at 9:09 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote: >> Hm, but what of the "null" value? Also, I get >> >> $ perl -e 'use warnings; use Test::More; ok("2017-01-01" != "null", "ok");' >> Argument "null" isn't numeric in numeric ne (!=) at -e line 1. >> Argument "2017-01-01" isn't numeric in numeric ne (!=) at -e line 1. >> ok 1 - ok
> It declares the test as "passed", right?
Oh! So it does. That is one darn weird behavior of the != operator.
Indeed! See this:
# first numeric matches, doesn't check beyond that
These tests show that the operator returns the correct result it finds a numeric value at the start of the string, either on LHS or RHS. Also, it will only compare the numeric values until first non-numeric character is found.
These two tests show why we saw no failure earlier. If neither LHS or RHS string has a starting numeric value, the operator declares the arguments as equal, irrespective of their values. I tested the same with == operator and that also exhibits the same behaviour. Weird and I wonder how it's not a source of constant bugs in perl code (I don't use perl a lot, so may be those who do are used to either turning warnings on or know this already.
There's still the point that we're not actually exercising this script in the buildfarm ...