Provided by: tcl8.6-doc_8.6.9+dfsg-2_all bug

NAME

       regexp - Match a regular expression against a string

SYNOPSIS

       regexp ?switches? exp string ?matchVar? ?subMatchVar subMatchVar ...?
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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
       subexpression  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  subexpression  count.   The  second  element is a list of
                      property names that describe various attributes of the regular  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 characters in the matching range of characters.

       -line          Enables newline-sensitive matching.  By default, newline  is  a  completely
                      ordinary  character  with no special meaning.  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 using -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 subexpression 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  argument 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 -indices 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 actually 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 prefixing 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(3tcl), regsub(3tcl), string(3tcl)

KEYWORDS

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