Programming

Operator Summary

MATLAB provides these operators for working with regular expressions:

• Character Classes
• Character Representation
• Logical Operators
• Lookaround Operators
• Quantifiers
• Token Operators
  
  

  Character Classes

  Operator	Usage
  .	Any single character, including white space
  [c1c2c3]	Any character contained within the brackets: c1 or c2 or c3
  [^c1c2c3]	Any character not contained within the brackets: anything but c1 or c2 or c3
  [c1-c2]	Any character in the range of c1 through c2
  \s	Any white-space character; equivalent to [ \f\n\r\t]
  \S	Any non-white-space character; equivalent to [^ \f\n\r\t]
  \w	Any alphabetic, numeric, or underscore character; equivalent to [a-zA-Z_0-9]
  \W	Any character that is not alphabetic, numeric, or underscore; equivalent to [^a-zA-Z_0-9]
  \d	Any numeric digit; equivalent to [0-9]
  \D	Any nondigit character; equivalent to [^0-9]

  
  
  

  Character Representation  

  Operator	Usage
  \a	Alarm (beep)
  \b	Backspace
  \e	Escape
  \f	Form feed
  \n	New line
  \r	Carriage return
  \t	Horizontal tab
  \v	Vertical tab
  \oN or \o{N}	Character of octal value N
  \xN or \x{N}	Character of hexadecimal value N
  \char	If a character has special meaning in a regular expression, precede it with backslash (\) to match it literally.

  
  
  

  Logical Operators

  Operator	Usage
  (expr)	Group regular expressions and capture tokens.
  (?:expr)	Group regular expressions, but do not capture tokens.
  (?>expr)	Group atomically.
  (?#expr)	Insert a comment into the expression. Comments are ignored in matching.
  expr1|expr2	Match expression expr1 or expression expr2.
  ^expr	Match the expression only at the beginning of the string.
  expr$	Match the expression only at the end of the string.
  \<expr	Match the characters when they start a word.
  expr\>	Match the characters when they end a word.
  \<expr\>	Match an exact word.

  
  
  

  Lookaround Operators

  Operator	Usage
  expr1(?=expr2)	Match expression expr1 if followed by expression expr2.
  expr1(?!expr2)	Match expression expr1 if not followed by expression expr2.
  (?<=expr1)expr2	Match expression expr2 if preceded by expression expr1.
  (?<!expr1)expr2	Match expression expr2 if not preceded by expression expr1.

  
  
  

  Quantifiers  

  Operator	Usage
  ?	Match the preceding element 0 times or 1 time. Equivalent to {0,1}.
  *	Match the preceding element 0 or more times. Equivalent to {0,}.
  +	Match the preceding element 1 or more times. Equivalent to {1,}.
  {n}	Must match exactly n times. Equivalent to {n,n}.
  {n,}	Must occur at least n times.
  {n,m}	Must occur at least n times but no more than m times.
  q?	Match the preceding element q times according to the guidelines stated above for lazy quantifiers, where q represents any one of the expressions shown in the top six rows of this table (e.g., {2,5}?).
  q+	Match the preceding element q times according to the guidelines stated above for possessive quantifiers, where q represents any one of the expressions shown in the top six rows of this table (e.g., {2,5}+).

  
  
  

  Token Operators

  Operator	Usage
  (expr)	Capture in a token all characters matched by the expression within the parentheses.
  \N	Match the Nth token generated by this command. That is, use \1 to match the first token, \2 to match the second, and so on.
  $N	Insert the match for the Nth token in a replacement string. Used only by the regexprep function.
  (?<name>expr)	Capture in a token all characters matched by the expression within the parentheses. Assign a name to the token.
  \k<name>	Match the token referred to by name.
  (?(tok)expr)	If token tok is generated, then match expression expr.
  (?(tok)expr1| expr2)	If token tok is generated, then match expression expr1. Otherwise, match expression expr2.

Handling Multiple Strings

Comma-Separated Lists

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