Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
regexp(n)		     Tcl Built-In Commands		     regexp(n)

______________________________________________________________________________

NAME
       regexp -	Match a	regular	expression against a string

SYNOPSIS
       regexp ?switches? exp string ?matchVar? ?subMatchVar subMatchVar	...?
______________________________________________________________________________

DESCRIPTION
       Determines  whether  the	 regular expression exp	matches	part or	all of
       string and returns 1 if it does,	0 if it	does not,  unless  -inline  is
       specified  (see	below).	  (Regular expression matching is described in
       the re_syntax reference page.)

       If additional arguments	are  specified	after  string  then  they  are
       treated	as the names of	variables in which to return information about
       which part(s) of	string matched exp.  MatchVar will be set to the range
       of  string that matched all of exp.  The	first subMatchVar will contain
       the characters in string	that matched the leftmost parenthesized	subex-
       pression	 within	 exp, the next subMatchVar will	contain	the characters
       that matched the	next parenthesized subexpression to the	right in  exp,
       and so on.

       If  the	initial	arguments to regexp start with - then they are treated
       as switches.  The following switches are	currently supported:

       -about	      Instead of attempting to match the  regular  expression,
		      returns  a list containing information about the regular
		      expression.  The first element of	the list is  a	subex-
		      pression	count.	 The second element is a list of prop-
		      erty names that describe various attributes of the regu-
		      lar  expression.	This  switch is	primarily intended for
		      debugging	purposes.

       -expanded      Enables use of the expanded  regular  expression	syntax
		      where  whitespace	and comments are ignored.  This	is the
		      same as specifying the (?x)  embedded  option  (see  the
		      re_syntax	manual page).

       -indices	      Changes what is stored in	the matchVar and subMatchVars.
		      Instead of storing the matching characters from  string,
		      each variable will contain a list	of two decimal strings
		      giving the indices in string of the first	and last char-
		      acters in	the matching range of characters.

       -line	      Enables newline-sensitive	matching.  By default, newline
		      is a completely ordinary character with no special mean-
		      ing.   With  this	flag, "[^" bracket expressions and "."
		      never match newline, "^" matches an empty	 string	 after
		      any  newline in addition to its normal function, and "$"
		      matches an empty string before any newline  in  addition
		      to  its  normal  function.   This	 flag is equivalent to
		      specifying both -linestop	and -lineanchor, or  the  (?n)
		      embedded option (see the re_syntax manual	page).

       -linestop      Changes the behavior of "[^" bracket expressions and "."
		      so that they stop	at newlines.   This  is	 the  same  as
		      specifying  the  (?p) embedded option (see the re_syntax
		      manual page).

       -lineanchor    Changes the behavior of "^" and "$" (the	"anchors")  so
		      they match the beginning and end of a line respectively.
		      This is the same as specifying the (?w) embedded	option
		      (see the re_syntax manual	page).

       -nocase	      Causes  upper-case characters in string to be treated as
		      lower case during	the matching process.

       -all	      Causes the regular expression  to	 be  matched  as  many
		      times  as	 possible  in  the string, returning the total
		      number of	matches	found.	 If  this  is  specified  with
		      match  variables,	 they will contain information for the
		      last match only.

       -inline	      Causes the command to return, as a list, the  data  that
		      would  otherwise be placed in match variables.  When us-
		      ing -inline, match variables may not be  specified.   If
		      used  with  -all,	 the list will be concatenated at each
		      iteration, such that a flat  list	 is  always  returned.
		      For  each	 match	iteration, the command will append the
		      overall match data, plus one element for each subexpres-
		      sion in the regular expression.  Examples	are:

			     regexp -inline -- {\w(\w)}	" inlined "
				   -_ in n
			     regexp -all -inline -- {\w(\w)} " inlined "
				   -_ in n li i	ne e

       -start index   Specifies	 a  character  index offset into the string to
		      start matching the regular  expression  at.   The	 index
		      value is interpreted in the same manner as the index ar-
		      gument to	string index.  When  using  this  switch,  "^"
		      will  not	 match	the beginning of the line, and \A will
		      still match the start of the string at index.   If  -in-
		      dices is specified, the indices will be indexed starting
		      from the absolute	beginning of the input string.	 index
		      will be constrained to the bounds	of the input string.

       --	      Marks  the end of	switches.  The argument	following this
		      one will be treated as exp even if it starts with	a -.

       If there	are more subMatchVars than parenthesized subexpressions	within
       exp,  or	if a particular	subexpression in exp does not match the	string
       (e.g. because it	was in a  portion  of  the  expression	that  was  not
       matched),  then the corresponding subMatchVar will be set to "-1	-1" if
       -indices	has been specified or to an empty string otherwise.

EXAMPLES
       Find the	first occurrence of a word starting with foo in	a string  that
       is not actually an instance of foobar, and get the letters following it
       up to the end of	the word into a	variable:

	      regexp {\mfoo(?!bar\M)(\w*)} $string -> restOfWord

       Note that the whole matched substring has been placed in	 the  variable
       "->",  which  is	a name chosen to look nice given that we are not actu-
       ally interested in its contents.

       Find the	index of the word badger (in any case)	within	a  string  and
       store that in the variable location:

	      regexp -indices {(?i)\mbadger\M} $string location

       This could also be written as a basic regular expression	(as opposed to
       using the default syntax	of advanced regular expressions) match by pre-
       fixing the expression with a suitable flag:

	      regexp -indices {(?ib)\<badger\>}	$string	location

       This counts the number of octal digits in a string:

	      regexp -all {[0-7]} $string

       This  lists  all	 words	(consisting of all sequences of	non-whitespace
       characters) in a	string,	and is useful as a more	 powerful  version  of
       the split command:

	      regexp -all -inline {\S+}	$string

SEE ALSO
       re_syntax(n), regsub(n),	string(n)

KEYWORDS
       match, parsing, pattern,	regular	expression, splitting, string

Tcl				      8.3			     regexp(n)

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | KEYWORDS

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=regexp.tcl87&manpath=FreeBSD+13.0-RELEASE+and+Ports>

home | help