Using Boundaries
Regex : cat

he cat scattered his food all over the room.

Sử dụng biên với \b
Regex : \bcat\b --> từ cat
The cat scattered his food all over the room.

Làm thế nào để định nghĩa giới hạn của 1 xâu bất kì ?
Vd : muốn lấy <xml version="1.0" ?>
trong : 
<?xml version="1.0" encoding="UTF-8" ?>

<wsdl:definitions targetNamespace="http://tips.cf"

xmlns:impl="http://tips.cf" xmlns:intf="http://tips.cf"

xmlns:apachesoap="http://xml.apache.org/xml-soap"

Regex : <\?xml.*\?> --> hay hơn có thể dùng ^\s*<\?xml.*\?>

<?xml version="1.0" encoding="UTF-8" ?>

<wsdl:definitions targetNamespace="http://tips.cf"

xmlns:impl="http://tips.cf" xmlns:intf="http://tips.cf"

xmlns:apachesoap="http://xml.apache.org/xml-soap"

Using Multiline Mode

Regex : (?m)^\s*//.*$

<SCRIPT>

function doSpellCheck(form, field) {

   // Make sure not empty

   if (field.value == '') {

      return false;

   }

   // Init

   var windowName='spellWindow';

   var spellCheckURL='spell.cfm?formname=comment&fieldname='+field. name;

   

   // Done

   return false;

}

</SCRIPT>

(?m) :