Checking whether a value is numeric or not

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

Hi, Using regex, I have taken a value and now I want to report a error message if it is not a numeric value. My lines are below:

if($_ =~ /<blk id="(.+?)"\/>/g)
   {
      my $blk=$1;
      if($blk != \d){print "Invalid value"}
   }
[download]

Now, whether the value is 1 or abc, I am not getting the error. It should accept 1 but not abc. Could anyone help me to identify what's wrong in the code?

Comment on Checking whether a value is numeric or not Download Code

Replies are listed 'Best First'.
Re: Checking whether a value is numeric or not by almut (Canon) on Nov 27, 2008 at 08:20 UTC
Regexp::Common might keep you from reinventing the wheel: `use Regexp::Common; while (<DATA>) { chomp; /^$RE{num}{real}$/ and print "$_ is a number\n"; } __DATA__ 123 abc 0.123` [download]	[reply] [d/l]
Re: Checking whether a value is numeric or not by Krambambuli (Curate) on Nov 27, 2008 at 08:08 UTC
Well, what exactly do you define as being a "numeric value" ? 7.89e-200 ? 0xabc ? They both are numeric values... If you think about a string of exclusive decimal digits, you might want to rewrite your test as `if($blk !~ /^[\d]+$/) {print "Invalid value"};` [download] or so. Krambambuli ---	[reply] [d/l]
Re^2: Checking whether a value is numeric or not by gwadej (Chaplain) on Nov 28, 2008 at 14:36 UTC
For this particular case, I would probably use: `if($blk =~ /\D/) { print "Invalid value";}` [download] For some reason, it seems clearer to me. G. Wade	[reply] [d/l]
Re: Checking whether a value is numeric or not by hda (Chaplain) on Nov 27, 2008 at 10:18 UTC
Hi, Why not try Scalar::Util ? `use Scalar::Util qw(looks_like_number); if (looks_like_number($your_number)) { do something; }` [download]	[reply] [d/l]
Re: Checking whether a value is numeric or not by Gangabass (Vicar) on Nov 27, 2008 at 08:25 UTC
`perldoc -q number` Use Super Search to quickly find answers to your questions	[reply] [d/l]