MorePHPfunctionsforusingregularexpressions.ppt

More PHP functions for using regular expressions Up to now, we have seen just one of the library of functions which PHP provides for using regular expressions The full library is described in Chapter CVIII of the PHP Manual We will consider just two more of them preg_match and preg_match_all preg_match The format of a call to this function is int preg_match ( string pattern, string subject [, array matches [, int flags [, int offset]]] ) As can be seen, only the first two arguments are required, so a minimum-argument call is of the form int preg_match ( string regexp, string subject) which returns 0 if the regexp is not matched inside the subject string, or 1 if the regexp is matched inside the string PHP code ?php $document = h1France/h1 pFoods of France: olliwine/lilibread/li/ol/p; $regexp = %p.+/p%; if ( preg_match($regexp,$document) ) { echo Yes; } else { echo No; } ? Output No Why no match? Answer: on next slide We need to make the dot match newlines Revised PHP code ?php $document = h1France/h1 pFoods of France: olliwine/lilibread/li/ol/p; $regexp = %p.+/p%s; if ( preg_match($regexp,$document) ) { echo Yes; } else { echo No; } ? Output Yes preg_match (contd.) Frequently, it is useful to use the third, optional, argument int preg_match ( string pattern, string subject, array matches ) As before, this returns o or 1 depending on whether a match was found in the subject string However, in addition, elements of the array in the third argument are set to match parts of the matching substring of the target string matches[0] is set to contain the whole substring matches[1] is set to contain the first () substring matches[2] is set to contain the second () substring … etc PHP code ?php $document = h1France/h1 pFoods of France: olliwine/lilibread/li/ol/p; e