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 doesn't, unless -inline is
specified (see below). (Regular expression matching is described in
the resyntax 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
resyntax manual page).
-indices Changes what is stored in the subMatchVars. Instead of
storing the matching characters from string, each vari-
able 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 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 `$'
matches an empty string before any newline in addition
to its normal function. This flag is equivalent to
specifying both -linestop and -lineanchor, or the (??n)
embedded option (see the resyntax manual page).
-linestop Changes the behavior of `[^' bracket expressions and `.'
so that they stop at newlines. This is the same as
specifying the (??p) embedded option (see the resyntax
manual page).
-lineanchor Changes the behavior of `^' and `$' (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 resyntax 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 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. 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 subMatchVar's than parenthesized subexpressions
within exp, or if a particular subexpression in exp doesn't match the
string (e.g. because it was in a portion of the expression that wasn't
matched), then the corresponding subMatchVar will be set to ``-1 -1''
if -indices has been specified or to an empty string otherwise.
SEE ALSO
resyntax(n), regsub(n)
KEYWORDS
match, regular expression, string
Tcl 8.3 regexp(n)
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