Replacing values within a string

Tcl has added a very useful keyword to the string command to simplify alteration of the string. The map keyword allows us to replace values within a string as passed without having to programmatically locate the target characters.

The syntax of the string command is as follows:

string map nocase mapping string

The string command will read the mapping provided and replace the affected values within the string. Mapping is passed as a valid Tcl list in a key-value pair format similar to that returned by performing a get on an array. Bear in mind that the string is only mapped once. If the optional nocase switch is provided, a case insensitive match will be made.

How to do it…

In the following example, we will replace every instance of a character set inside a string. Return values from the commands are provided for clarity. Enter the following command:

% string map {abc def} abcabcabc
defdefdef

How it works…

Tcl has mapped each occurrence of the string "abc" and...