regsub(n) Tcl Built-In Commands regsub(n)
regsub - Perform substitutions based on regular expression pattern matching
regsub ?switches? exp string subSpec varName
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 substitution with the portion of string that matched the n-th parenthe-
sized subexpression of exp. Additional backslashes may be used in subSpec to prevent spe-
cial interpretation of ``&'' or ``\0'' or ``\n'' or backslash. The use of backslashes in
subSpec tends to interact badly with the Tcl parser's use of backslashes, so it's gener-
ally 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 substitution is performed for
each of these ranges. Without this switch only the first matching range is
found and substituted. If -all is specified, then ``&'' and ``\n'' sequences
are handled for each substitution using the information from the corresponding
-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 METASYNTAX, below).
-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 `$' matches an empty
string before any newline in addition to its normal function. This flag is
equivalent to specifying both -linestop and -lineanchor, or the (?n) embed-
ded option (see METASYNTAX, below).
-linestop Changes the behavior of `[^' bracket expressions and `.' so that they stop
at newlines. This is the same as specifying the (?p) embedded option (see
-lineanchor Changes the behavior of `^' and `$' (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.
match, pattern, regular expression, substitute
Tcl 8.3 regsub(n)