What is Regsub command in Tcl?

What is Regsub command in Tcl?

regsub, a built-in Tcl command, performs substitutions based on regular expression pattern matching.

How do I write data into a TCL file?

Tcl – File I/O

1. Opening Files. Tcl uses the open command to open files in Tcl.
2. Closing a File. To close a file, use the close command.
3. Writing a File. Puts command is used to write to an open file.
4. Reading a File. Following is the simple command to read from a file − set file_data [read $fp]

How do you find the substring of a string in TCL?

The string command Use ‘first’ or ‘last’ to look for a substring. The return value is the index of the first character of the substring within the string. The ‘string match’ command uses the glob-style pattern matching like many UNIX shell commands do. Matches any number of any character.

What does + S+ mean?

The Difference Between \s and \s+ For example, expression X+ matches one or more X characters. Therefore, the regular expression \s matches a single whitespace character, while \s+ will match one or more whitespace characters.

When to use the regexp command in Tcl?

The “regexp” command is used to match a regular expression in Tcl. A regular expression is a sequence of characters that contains a search pattern. It consists of multiple rules and the following table explains these rules and corresponding use.

Is there a regular expression engine in Tcl 8.1?

That’s because Tcl 8.1 (apart from the regular expression engine) implements only the Unicode locale (where all characters sort in Unicode order, there are no multi-character collating elements and no equivalence classes). This document has an overview of the new regular expression features.

Which is the first element of a list in regexp?

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.

What is the second element of the regexp manual page?

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).