On Mon, May 17, 2021 at 08:42:11AM -0500, Peng Yu via Libc-help wrote:
> Hi,
> 
> It seems that regex.h does not support lookahead. Is it so? Thanks.

You mean those "look ahead" i.e. (?=...) viz. (?!...) and "look behind",
i.e. (?<=...) viz. (?<!...) assertions of PCRE?

As far as I know, no. Regex.h supports exactly POSIX (extended) regular
expressions.

Cheers
 - t