regsub
regsub(n) Tcl Built-In Commands regsub(n)
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NAME
regsub - Perform substitutions based on regular expression pattern
matching
SYNOPSIS
regsub ?switches? exp string subSpec varName
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DESCRIPTION
This command matches the regular expression exp against string, and it
copies string to the variable whose name is given by varName. (Regular
expression matching is described in the re_syntax reference page.) If
there is a match, then while copying string to varName the portion of
string that matched exp is replaced with subSpec. If subSpec contains
a ``&'' or ``\0'', then it is replaced in the substitution with the
portion of string that matched exp. If subSpec contains a ``\n'',
where n is a digit between 1 and 9, then it is replaced in the substi-
tution with the portion of string that matched the n-th parenthesized
subexpression of exp. Additional backslashes may be used in subSpec to
prevent special interpretation of ``&'' or ``\0'' or ``\n'' or back-
slash. The use of backslashes in subSpec tends to interact badly with
the Tcl parser's use of backslashes, so it's generally safest to
enclose subSpec in braces if it includes backslashes.
If the initial arguments to regexp start with - then they are treated
as switches. The following switches are currently supported:
-all All ranges in string that match exp are found and substitu-
tion is performed for each of these ranges. Without this
switch only the first matching range is found and substi-
tuted. If -all is specified, then ``&'' and ``\n'' sequences
are handled for each substitution using the information from
the corresponding match.
-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 META-
SYNTAX, below).
-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 `$'
matches an empty string before any newline in addition
to its normal function. This flag is equivalent to
specifying both -linestop and -lineanchor, or the (?n)
embedded option (see METASYNTAX, below).
-linestop Changes the behavior of `[^' bracket expressions and `.'
so that they stop at newlines. This is the same as
specifying the (?p) embedded option (see METASYNTAX,
below).
-lineanchor Changes the behavior of `^' and `$' (the ``anchors'') so
they match the beginning and end of a line respectively.
This is the same as specifying the (?w) embedded option
(see METASYNTAX, below).
-nocase Upper-case characters in string will be converted to lower-
case before matching against exp; however, substitutions
specified by subSpec use the original unconverted form of
string. |
-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. 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 -.
The command returns a count of the number of matching ranges that were
found and replaced. See the manual entry for regexp for details on the
interpretation of regular expressions.
SEE ALSO
regexp(n), re_syntax(n)
KEYWORDS
match, pattern, regular expression, substitute
Tcl 8.3 regsub(n)
