Re^2: Lookahead assertion

[BrowserUk]

When the engine sees that it should try again because of the /g, it steps one character past where last it tried.

This explains why the final . in BrowserUk’s solution is not strictly necessary

Indeed. The final '.' is not necessary with Perl's regex engine.

But many other regex libraries -- including some that claim to be Perl-compatible -- do not have this pragmatic deviation from the classical regular expression operation; hence it has become a habit with me to do this explicitly.

[talexb]

Thanks for your reply .. and I checked, the final dot makes no difference in the result ..

  DB<6> @w3 = ( $foo =~ /(?=(\d{3}))/g );

  DB<7> x @w3
0  123
1  234
2  345
3  456
4  567
5  679
6  790
  DB<8> @w3 = ( $foo =~ /(?=(\d{3}))./g );

  DB<9> !7
x @w3
0  123
1  234
2  345
3  456
4  567
5  679
6  790

Good to know.