regexp

Match a regular expression against a string 

Tclsh Built-In Commands

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 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.

-indices 

Changes what is stored in the 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.

-linestop 

Changes the behavior of [^ bracket expressions and . so that they stop at newlines. This is the same as specifying the (?p) embedded option.

-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.

-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 continue 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. 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 (for example, 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.

PORTABILITY

Windows 10. Windows Server 2016. Windows Server 2019. Windows 11. Windows Server 2022. Windows Server 2025.

AVAILABILITY

PTC MKS Toolkit for Power Users
PTC MKS Toolkit for System Administrators
PTC MKS Toolkit for Developers
PTC MKS Toolkit for Interoperability
PTC MKS Toolkit for Professional Developers
PTC MKS Toolkit for Enterprise Developers
PTC MKS Toolkit for Enterprise Developers 64-Bit Edition

SEE ALSO

Commands:
re_syntax

PTC MKS Toolkit 10.5 Documentation Build 40.