From 623d77caec9639b94505b72f7c2cbd21a97e3812 Mon Sep 17 00:00:00 2001 From: steve Date: Sat, 14 Feb 1998 18:26:29 +0000 Subject: Note that '+' and '?' are not special characters in basic REs but they can be simulated using bounds. PR: 5708 Submitted by: Oliver Fromme --- lib/libc/regex/re_format.7 | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'lib/libc/regex') diff --git a/lib/libc/regex/re_format.7 b/lib/libc/regex/re_format.7 index db2f634..d663f11 100644 --- a/lib/libc/regex/re_format.7 +++ b/lib/libc/regex/re_format.7 @@ -222,8 +222,11 @@ as an implementation can refuse to accept such REs and remain POSIX-compliant. .PP Obsolete (``basic'') regular expressions differ in several respects. -`|', `+', and `?' are ordinary characters and there is no equivalent -for their functionality. +`|' is an ordinary character and there is no equivalent +for its functionality. +`+' and `?' are ordinary characters, and their functionality +can be expressed using bounds (\&{1,\&} or \&{0,1\&} respectively). +Also note that `x+' in modern REs is equivalent to `xx*'. The delimiters for bounds are `\e{' and `\e}', with `{' and `}' by themselves ordinary characters. The parentheses for nested subexpressions are `\e(' and `\e)', -- cgit v1.1