Try ^[-+]?0[Xx][[:xdigit:]]++(?![.G-Zg-z])
Note the additional '+'. This ensures that once it has matched the xdigits, it does not release any of them. Regards, Philip On Mon, 24 May 2021 at 04:33, Peng Yu via Pcre-dev <pcre-dev@exim.org> wrote: > I use the following regex. > > ^[-+]?0[Xx][[:xdigit:]]+(?![.G-Zg-z]) > > and the following string > > 0x10g > > on using PCRE. > > https://regex101.com/ > > It matches 0x1. I want it to be no match. Is there a way to modify the > regex so that only matches valid hex numbers? Thanks. > > -- > Regards, > Peng > > -- > ## List details at https://lists.exim.org/mailman/listinfo/pcre-dev > -- ## List details at https://lists.exim.org/mailman/listinfo/pcre-dev