Symbols used in Regular Expressions in Php

(1)         Using ^ and $:

ð   The ^ symbol indicate the start of a string and $ symbol indicate the

end of a string.

ð   For example:

ð    “^Shah”: matches any string that starts with Shah.

ð   “Shah$”: Matches any string that ends with Shah.

ð   “^Shah$”: Matches any string that starts and ends with Shah.

ð   “Analyst”: matches any string that has the text Analyst.

(2)       Using *, + and ?

ð   The symbols like “*‟, “+‟ and “?‟, denote the number of times a character or a sequence of characters may occur. The “*‟ means zero or more, “+‟ means one or more and “?‟ means zero or one.

ð    For example:

1) “sh*”: Matches a string that has a character s followed by zero or more h. The possibilities are “s”, “sh”, “shh” and so on.

2)  “sh+”: Matches a string that has a character s followed by at least

one or more h. The possibilities are “sh”, “shh” and so on.

3) “sh?”: Matches the string that may have a character s but may or may not be followed by a single character h. The possibilities are “s”,

“sh”.

4)  “s?h+$”: Matches the string that may have a character s but compulsory ends with at least one or more h. The possibilities are “h”, “sh”, “shh”, “shah” and so on.

(3)      Using Bounds { }

ð   Bounds can also be used which come inside braces and indicate ranges in the terms of occurrences.

ð   For example:

1)“sh{2}”: Matches a string that has character s followed by exactly two h. The possibility is “shh”.

2) “sh{2 ,}”: Matches a string that has a character s followed by at least two h. The possibilities are “shh”, “shhh” and so on.

3) “sh{3,5}”: Matches a string that has a character s followed by at least three but not more tha five h. The possibilities are “shhh”,

“shhhh”, “shhhhh”.