Matching literal (normal) text characters with Regular Expressions
Basically regex are used to search a character, word, string or string pattern. Here we are going to search for a single literal character. Consider we want search for "o" in the string patter "Poonam like mango". It will match the "o" after the "P". The default behavior of most regular expression engines is to return just the first match. Though this regex can match the second "o" too. Most regex implementations provide a mechanism by which we can obtain a list of all matches when the regex engine start searching through the string after the first match.