Unless I'm hopelessly wrong, for starters I think you have step one wrong.

I think step one should be something like match either 0 or 1(01*0)*1. The final asterisk matches zero or more of one of the matched branch or atom so that's how it matches 00.

If this was your stumbling block, hopefully I've helped!

In reply to Re: Re: Regex refresher by zakb
in thread Regex refresher by FoxtrotUniform

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