Is a vble a number?

mw55309 has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: Is a vble a number? by Limbic~Region (Chancellor) on Oct 23, 2003 at 12:31 UTC
mw55309, Scalar::Util has looks_like_a_number. Here is the source: `sub looks_like_number { local $_ = shift; # checks from perlfaq4 return 1 unless defined; return 1 if (/^[+-]?\d+$/); # is a +/- integer return 1 if (/^([+-]?)(?=\d\|\.\d)\d(\.\d)?([Ee]([+-]?\d+))?$/); # +a C float return 1 if ($] >= 5.008 and /^(Inf(inity)?\|NaN)$/i) or ($] >= 5.006 +001 and /^Inf$/i); 0; }` [download] As you can see, it handles the regex from the FAQ plus a few additional things. Cheers - L~R	[reply] [d/l]
Re: Is a vble a number? by broquaint (Abbot) on Oct 23, 2003 at 11:09 UTC
To be sure, you could always ask perl. Otherwise you could look into using the various number regexes found in the always useful `Regexp::Common`. HTH `_________ broquaint`	[reply]
Re: Is a vble a number? by Abigail-II (Bishop) on Oct 23, 2003 at 11:06 UTC
`$ perldoc -q float` [download] Abigail	[reply] [d/l]
Re: Is a vble a number? by RMGir (Prior) on Oct 23, 2003 at 11:53 UTC
Looking at the title, I couldn't figure out what mw55309 was asking. All I could think of was "vbles vobble but they don't fall down" :) By the way, "0.234+E06" isn't a valid number, or at least, it isn't 234000. perl won't complain, but it evaluates to 0.234. You probably meant "0.234E+06". Abigail-II is right, as usual; the regexen in the FAQ answer would catch that error. Mike	[reply]
Re: Is a vble a number? by zentara (Cardinal) on Oct 23, 2003 at 16:15 UTC
`#!/usr/bin/perl #gives correct output for your examples print is_numeric(10),"\n"; print is_numeric('3rd'),"\n"; print is_numeric("NA"),"\n"; print is_numeric(2.34),"\n"; print is_numeric(0.234+E06),"\n"; sub is_numeric { no warnings; use warnings FATAL => 'numeric'; return defined eval { $_[ 0] == 0 }; }` [download]	[reply] [d/l]
Re: Is a vble a number? by demerphq (Chancellor) on Oct 23, 2003 at 12:33 UTC
Really depends on how you define a number. If you want perls definition then use Scalar::Util's looks_like_number() otherwise use one of the regex solutions mentioned already. --- demerphq _{First they ignore you, then they laugh at you, then they fight you, then you win. -- Gandhi}	[reply] [d/l]