match zeros including decimals with RegEx .NET

Question

I have a textbox that accepts up to 7 characters. I need to make sure the value isn't accepted if it is all zeros before and/or after the decimal place, but i can't figure out the pattern

e.g 000, 00.000, 0.0000 etc.

cases such as 0.001, 0.1 etc can be allowed

have tried ^[0] but this didnt allow for single zero, or didnt allow for combinations such as 0.001

Answer 1

^(?=.*[1-9])\d+(\.\d+)?$

This regex will accept strings meeting the following conditions:

• There must be a digit from 1-9 in the string - (?=.*[1-9])
• It must begin with one or more digits - \d+
• It may optionally end with a period and one or more digits - (\.\d+)?

It will match these strings:

• 42
• 42.42

It will not match these strings:

• 0
• 0.0
• 42.
• .42

See it in action here.