Regex match number containing at least one time [1-9]-CodePudding

So I need this for validating a part of a telephone number. How can I check if [0-9]{5} also includes at least once [1-9]?

Positive:

Negative:

00000
123456

CodePudding user response：

You can do this:

^[0-9]*[1-9] [0-9]*$

Optionally starting (^[0-9]*) and optionally ending ([0-9]*$) with anything from 0-9, and somewhere in between at least one digit without zero [1-9]

Edit:

My answer was missing the length of the input. Thanks to CarySwoveland for helping out using lookarounds:

You can either use positive lookahead to make sure at least one non-zero digit is contained in the input:

^(?=.*[1-9])\d{5}$

Or invert it to negative lookahead to avoid the zero-only input:

^(?!00000)\d{5}$

However, changing the negative lookahead requires you to update the number of zeros and the digit count \d{n}. This becomes harder the longer the input gets. Therefore, I would recommend using the positive lookahead.