Re: Help with regular expressions

Hi Daniel, "José daniel ramos wey" ... > Hi! I´m new to regular expressions, and it seems to be an art to make it > work as expected. > > I´m trying to remove all "single-line" comments from an string - that´s > everything after "//" to the end of a line. I expected that this would do > the job: ereg_replace("//[[:alnum:]]*\n","",$string), but it didn´t work. > > Any tips? First off, IMO, you're better off using pcre regex functions than the posix ones: http://www.php.net/preg_replace <? $string = "// line 1\nNormal line\n// line 2 with a few odd characters\"£$%^&*()_\nAnother normal line."; $string = preg_replace('!^//.*$!m', '', $string); echo $string; ?> Your regex is basically saying this: //[[:alnum:]]*\n Match anywhere in the string (you have no anchor as to where the // should start), consume anything that is alphanumeric (0 through 9, a through z), as many times as they occur, followed by a new line. Thus, your regex would consume stuff like this: //sdfffffffffffffffffffffffffffffffffdfffsdfsdfsdddddd12345678900987sdfsdbfs but not // sdfffffffffffffffffffffffffffffffffdfffsdfsdfsdddddd12345678900987sdfsdbfs or // this is a comment. as for my example, I'm using exclamation marks as the delimiters, the m modifier which matches $ at the end of every newline, and ^ at the start of every new line. So: !^//.*$!m Means ^ at the start of the line // if there are two of these .* match everything $ up to the end of the new line and replace it with nothing. Check the pattern modifiers etc in the manual. HTH ~James