Scalar::Util provides an excellent looks_like_number function.

use Scalar::Util qw< looks_like_number >;
use Test::More tests => 6;

ok looks_like_number '1';
ok looks_like_number '123';
ok looks_like_number '-123';
ok looks_like_number '1.0';
ok looks_like_number '123.0';
ok looks_like_number '-123.0';
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View the source for Scalar::Util::PP - it's got a few regular expressions you could probably borrow.

Thank you. That is a useful function! I ended up answering my own question for a regex that includes negative/positive integers and negative/positive floating points.

/^(?:|-|\d+|-\d+|\d+.|-\d+\.|\d+\.\d+|-\d+\.\d+)$/
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And just for clarification, this is used as a -validatecommand.

Did you know that regexp matches:

• -
• 1.

But fails to match:

• .1
• -.1

You might want to try this. It's somewhat simpler than yours, and it disallows the single hyphen, but allows decimals which start with the decimal point and no preceding 0.

/^[-]?(?:[.]\d+|\d+(?:[.]\d*)?)$/
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Or if you consider a leading/trailing decimal point to be an error, it can be made simpler:

/^[-]?\d+(?:[.]\d+)?$/
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perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'