Re: preg_replace brain teaser

Hello I finally figured out whay php is complaining. After all it wasn't an error with my regex rather it was an error how the regex gets interpreted by php before being send to the regex enginge. Recall my pattern was: 1: '(?<!\\)\{([a-zA-Z0-9_-]+?)\}' // in single quotes unlike in my posting This is allright if it would be transfered like this to the regex engine. But what I've forgotten is that a \ has to be escaped in singel quoted strings too. So in order to get the pattern 1 it has to be changed to 2: '(?<!\\\\)\\{([a-zA-Z0-9_-]+?)\\}' Now every \\ will be replaced by a singel \ when php interprets the string yielding the pattern 1. Which is then given to the regex engine which will again interpret the \\ as a \. SO keep that in mind when construction regex since there is no pointer in the manual stating this! A user comment is pointing to the fact but he is falsly deemed wrong by a second poster. (Lots of confusion there!!!) Also php seems to be fault tolerant in the interpretation and will see a single '\' as a '\' if it is not followed by a known meta character! In some cases this might seem as a feature but in the end IMHO it causes more confusion : ). My tip is to echo the pattern to the screen to see how it is passed to the regex engine. Regards Stefan Langer