DOKK / manpages / debian 11 / tcl8.6-doc / regexp.3tcl.en
regexp(3tcl) Tcl Built-In Commands regexp(3tcl) 







regexp - Match a regular expression against a string








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










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:



  

  
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.

  

  
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).

  

  
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.

  

  
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).

  

  
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).

  

  
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).

  

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

  

  
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.

  

  
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







  

  
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.








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










re_syntax(3tcl), regsub(3tcl), string(3tcl)








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







  

    8.3
    Tcl