Beefy Boxes and Bandwidth Generously Provided by pair Networks
P is for Practical
 
PerlMonks  

Re: Re: Is it a number?

by broquaint (Abbot)
on Nov 12, 2002 at 00:19 UTC ( #212159=note: print w/ replies, xml ) Need Help??


in reply to Re: Is it a number?
in thread Does it look like a number?

Ah yes, that would be

sub is_numeric { ($_[0] & ~ $_[0]) eq "0"; }
Which tests whether a scalar is a numeric value or a string value e.g 42 vs "42". Whereas the snippet discerns whether a given scalar looks like a number or not e.g
print +(isnum($_) ? "is a number" : "not a number"), ": $_", $/ for qw( 1 2.2 3e3 4. .5); __output__ is a number: 1 is a number: 2.2 is a number: 3e3 is a number: 4. is a number: .5

HTH

_________
broquaint


Comment on Re: Re: Is it a number?
Select or Download Code
Replies are listed 'Best First'.
•Re: Re: Re: Is it a number?
by merlyn (Sage) on Oct 23, 2003 at 14:50 UTC
    Yeah, the difference is the difference between "could this string be converted into a number without getting the warnings if -w is on?" vs "is this value always and only a number?". Everything in the latter case is also true for the former, but the inverse is not true. For example, all external data read from filehandles is always a string initially, so it could never pass this "is_numeric" test.

    -- Randal L. Schwartz, Perl hacker
    Be sure to read my standard disclaimer if this is a reply.

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://212159]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others musing on the Monastery: (5)
As of 2015-07-30 02:28 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (269 votes), past polls