PHP - Regular Expression

^

The ^ Symbol indicates the start of a string for example "^Veewom" matches any string that start with Veewom.

$

The $ symbols indicates the end of a string for example "Veewom$" matches any string that ends with Veewom.

*

The symbols * denotes zero or more number of times a character or a sequence of characters may occur for example "ts*" matches a string that has a character t followed by zero or more s.

+

The symbol + denotes one or more number of times a character or a sequence of character may occur for example "ts+" matches a string that has a character s followed by at least one or more s.

?

The symbol ? denotes zeor or one character may occur for example "ts?" matches the string that may have a character t but may or may not be followed by single character s.

{}

Bounds can also be used which come inside braces and indicate ranges in the terms of occurrences for example "ts{2} matches a string that has character t followed by exactly two s.

()

To quantify a sequence of characters,put them inside round brackets for example "t(ss)*" matches a string that has a character t followed by zero or more copies of the sequence "ss".

|

The "|" symbol works similar to the OR operator for example "ts|pl" matches a string that holds either "ts" or "pl".

.

A period "." stands for any single character for example "t.[0-9]" matches a string that has a character s followed by any one character further followed by a digit.

[]

Bracket expression specify which characters are allowed in a single position of a string for example "[ts]" matches a string that has either character t or s.