regular expression match question

A script like this: line1: $string3 = bacdeabcdefghijklabcdeabcdefghijkl; line2: $string4 = xxyyzzbatttvv; line3: print \$1 = $1 [EMAIL PROTECTED],$+[0]}, \$ = $\n if($string3 =~ /(a|b)*/); line4: print \$1 = $1 [EMAIL PROTECTED],$+[0]}, \$ = $\n

Re: regular expression match question

On Jul 29, Pine Yan said: line1: $string3 = bacdeabcdefghijklabcdeabcdefghijkl; line2: $string4 = xxyyzzbatttvv; line3: print \$1 = $1 [EMAIL PROTECTED],$+[0]}, \$ = $\n if($string3 =~ /(a|b)*/); line4: print \$1 = $1 [EMAIL PROTECTED],$+[0]}, \$ = $\n

RE: regular expression match question

line1: $string3 = bacdeabcdefghijklabcdeabcdefghijkl; line2: $string4 = xxyyzzbatttvv; line3: print \$1 = $1 [EMAIL PROTECTED],$+[0]}, \$ = $\n if($string3 =~ /(a|b)*/); line4: print \$1 = $1 [EMAIL PROTECTED],$+[0]}, \$ = $\n if($string4 =~ //); $1 = a

RE: regular expression match question

On Jul 29, Pine Yan said: line1: $string3 = bacdeabcdefghijklabcdeabcdefghijkl; line2: $string4 = xxyyzzbatttvv; If the regexp says match zero or more of (a or b), why can't we match an empty string in the first place? What causes (a|b)* to make no difference from (a|b)+?

Re: regular expression match question

Pine Yan wrote: A script like this: line1: $string3 = bacdeabcdefghijklabcdeabcdefghijkl; line2: $string4 = xxyyzzbatttvv; line3: print \$1 = $1 [EMAIL PROTECTED],$+[0]}, \$ = $\n if($string3 =~ /(a|b)*/); line4: print \$1 = $1 [EMAIL PROTECTED],$+[0]}, \$

RE: regular expression match question

The regex /[ab]*/ on the string bad matches 'ba' because regexes are greedy by default. They want to match as MUCH as they can. BUT regexes also try to find the earliest match in the string. This is why /[ab]*/ on the string cab matches ''. Because the engine found a successful match of 0

RE: regular expression match question

- From: Tom Allison [mailto:[EMAIL PROTECTED] Sent: Friday, July 29, 2005 3:23 PM To: beginners@perl.org Subject: Re: regular expression match question Pine Yan wrote: A script like this: line1: $string3 = bacdeabcdefghijklabcdeabcdefghijkl; line2: $string4 = xxyyzzbatttvv

RE: regular expression match question

On Jul 29, Pine Yan said: line3: print \$1 = $1 [EMAIL PROTECTED],$+[0]}, \$ = $\n if($string3 =~ /(a|b)*/); line4: print \$1 = $1 [EMAIL PROTECTED],$+[0]}, \$ = $\n if($string4 =~ //); $1 = a @{0,2}, $ = ba $1 = @{0,0}, $ = I'll go over it again.

RE: regular expression match question

No more questions. :D Sincerely Pine -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response