Regex for positive float numbers

Question

For example:
10
0.1
1.23234
123.123
0.000001
1.000
.3

And wrong examples:
0001.2
-12
-1.01<

Answer 1

I've stumbled on this page a few times, here is my solution for any one who stumbles here after me:

A regex like a=(\d+\.?\d* | \d*\.?\d+) matches all decimals numbers without a sign but includes things like 002.0

A regex to filter those things are b=[1-9\.]+.*

So one solution is to say it matches the criteria if a & b matches. Or equivalently (contrapositive), see if there is no match for !a | !b. Unfortunately, most languages don't have a complete regex package; the 'and' and negate functions of regular languages isn't present usually. Two simple regexes I've found in code looks a lot nicer and are more maintainable than one complex one (I say this in context to this question & similar situations)