Trimming a string
When writing a program, there is no way to ensure that only correctly formatted data is provided. An end-user may inadvertently enter whitespace, a test file may contain whitespaces, and so on. To address this issue, Tcl provides keywords to trim the undesirable whitespaces or characters if specified. The first of these is the trim keyword.
The syntax of the string command is as follows:
string trim string characters
If no characters are provided, the trim keyword will return the string with all leading and trailing whitespace trimmed. If the characters are not specified (specifying the characters is optional), only those whitespaces will be removed.
How to do it…
In the following example, we will trim the .gif extension from a string. Return values from the commands are provided for clarity. Enter the following command:
% string trim "picture.gif " .gif picture
How it works…
As you can see, Tcl has returned our trimmed string.
