I have the following regex to match a number:

^[ -]?[0-9]*\.?[0-9]*(E[ -]?[0-9]*)?$

Shown here: https://regex101.com/r/aAosEj/1. However, this also matches the empty dot, .. Is there a simple way to improve this regex for that, or do I need to handle the case in two ways, one which does num?.num and another which does num.?

CodePudding user response：

Nothing too simple here, but not too bad...

You need two cases, digits (. digits*)? OR . digits You also need to fix the exponent, which must be present if the E is used.

^[ -]?([0-9] (\.[0-9]*)?|\.[0-9] )(E[ -]?[0-9] )?$