PHP Regular Expression

In string match, one Regular Expression pattern can usually match multiple strings which is sometimes very useful. Regular Expression functions include preg_match(), preg_replace(), preg_split() etc.

<?PHP
	$arr = array("Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday");
	foreach($arr as $dy)
	{
	   if (preg_match("/t.?u/i",$dy))
	   echo "$dy\n";
	}
	Tuesday
	Thursday
	Saturday 
?>


Regular Expression Syntax:

Syntax
Description
\d
Digit, 0,1,2 ... 9
\D
Not Digit
\s
Space
\S
Not Space
\w
Word
\W
Not Word
\t
Tab
\n
New line
^
Beginning of the string
$
End of the string
\
Escape special characters, e.g. \\ is "\", \+ is "+"
|
Alternation match. e.g. /(e|d)n/ matches "en" and "dn"
Any character, except \n or line terminator
[ab]
a or b
[^ab]
Any character except a and b
[0-9]
All Digit
[A-Z]
All uppercase A to Z letters
[a-z]
All lowercase a to z letters
[A-z]
All Uppercase and lowercase a to z letters
i+
i at least one time
i*
i zero or more times
i?
i zero or 1 time
i{n}
i occurs n times in sequence
i{n1,n2}
i occurs n1 - n2 times in sequence
i{n,}
i occures >= n times
\0
NUL
\f
Form feed character
\r
Carriage return character
\v
Vertical tab
\xhhhh
Unicode with 4 characters of hexadecimal code hhhh
\xhh
Character with 2 characters of hexadecimal code hh
?=i
Lookahead matches only if i is followed
?!i
Lookahead matches only if i is not followed

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