How to use the character class

The character class

       $string = 'The product code is MBT-3461.'; 
       preg_match('/MB[TF]/', $string); // Matches MBT and returns 1
       preg_match('/[.]/', $string); // Matches . and returns 1
       preg_match('/[13579]/', $string); // Matches 3 and returns 1

Metacharacters inside a character class

Character	Example	Meaning
^	[^aeiou]	Negates the list of characters inside the character class
-	[a-z]	Creates a range of characters based on their Latin-1 character set values

Metacharacters

      preg_match('/MB[^TF]/', $string); // Matches nothing and returns 0
      preg_match('/MBT[^^]/', $string); // Matches MBT- and returns 1
      preg_match('/MBT-[1-5]/', $string); // Matches MBT-3 and returns 1
      preg_match('/MBT[_*-]/', $string)  // Matches MBT- and returns 1

How to use bracket expressions in a character class

Pattern	Matches
[:digit:]	Digits (same as \d)
[:lower:]	Lowercase letters
[:upper:]	Uppercase letters
[:letter:]	Upper-and lowercase letters
[:alnum:]	Upper-and lowercase letters and digits
[:word:]	Upper-and lowercase letters, digits, and the underscores (same as \w)
[:print:]	All printable characters including the space
[:graph:]	All printable characters excluding the spacet
[:punct:]	All printable characters excluding letters and digits

    Description
      A character class lets you match a single character from a list of possible characters.
Most characters with a special meaning lose it inside the brackets. The caret and dash are the only characters that retain their special meanings, and they are position dependent.
You can use a bracket expression inside a character class for several predefined character ranges, and you can combine several bracket expressions in one character class.

    

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