Re: How to determine if something is numeric?

[Ovid]

If I've understood your specs correctly:

use Scalar::Util 'looks_like_number';

if (0 != substr($var,0,1) and looks_like_number($var)) {
    # it's a number
}

Update: As sporty pointed out below, this breaks on negative numbers. I didn't see that dash in your post. Here's the fix:

use Scalar::Util 'looks_like_number';

if ($var !~ /^-?0/ && looks_like_number($var)) {
    # it's a number
}

[mifflin]

we must have different versions of something.
when I run that code id get the following error

erickn@hestia:/home/erickn/wo> perl x "looks_like_number" is not exported by the Scalar::Util module Can't continue after import errors at x line 5 BEGIN failed--compilation aborted at x line 5.

line 5 is the use line

I'm using perl 5.8.0
It looks like Scalar::Util uses List::Util and that version in my system is 1.07_00
any ideas?

[Limbic~Region]

mifflin,
looks_like_number was introduced in version 1.10 of Scalar::Util. The sub looks like this:

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;
}

As I stated in my reply - I do not think this meets your requirements because it also handles decimals, scientific notation, NaN, and Inf.

Cheers - L~R

[PodMaster]

It looks like Scalar::Util uses List::Util and that version in my system is 1.07_00 any ideas?

Upgrade :)

[exussum0]

This breaks on negative numbers.