"\0" in PCRE RegEx in PHP

Asked May 17 '16 at 14:37

Active May 17 '16 at 14:37

Viewed 68 times

 <?php
  $pattern = "/http:\\/\\/(([A-Za-z0-9.\-])*)/";
  $text = "http://www.google.com";
  $text = preg_replace($pattern,"<a href=\"\\0\">\\0</a>",$text);
  echo $text;
 ?>

The code above gets the URL from a string variable and adds an HTML tag for a link. So "http://www.google.com" becomes "<a href="http://www.google.com">http://www.google.com</a>". My question is how "\0" is something like placeholder for the value of the parameter "$text" in the "preg_repace" function, after it means NULL or 0x0?

asked May 17 '16 at 14:37

PetarZ

1

``"\\0"`` ([=``'\0'``](https://ideone.com/5N8Ior)) is a [backreference](http://www.regular-expressions.info/replacebackref.html) to the whole match. – Wiktor Stribiżew May 17 '16 at 14:41
There is an answer [here](http://stackoverflow.com/a/31874/3832970). – Wiktor Stribiżew May 17 '16 at 14:48
Use single quotes and change your delimiter, then you won't need as much escaping. `'~http://(([A-Za-z0-9.\-])*)~'`. – chris85 May 17 '16 at 14:50

"\0" in PCRE RegEx in PHP

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