- Tcl/Tk 8.5 Programming Cookbook
- Copyright
- Credits
- About the Author
- Acknowledgment
- About the Reviewers
- www.PacktPub.com
- Preface
- 1. The Tcl Shell
- 2. Using the Building Blocks Control Constructs
- 3. Error Handling
- 4. Handling String Expressions
- Introduction
- Appending to a string
- Formatting a string
- Matching a regular expression within a string
- Performing character substitution on a string
- Parsing a string using conversion specifiers
- Determining the length of a string
- Comparing strings
- Comparing a string of characters
- Locating the first instance of a character
- Locating the index of a character
- Determining the class of a string
- Locating the last instance of a string
- Determining the size of a string
- Replacing values within a string
- Locating a pattern within a string
- Returning a range of characters from a string
- Creating a string of repeated characters
- Replacing ranges of characters contained within a string
- Creating a reverse string
- Converting a string to lowercase
- Converting a string to title
- Converting a string to uppercase
- Trimming a string
- Trimming leading whitespace
- Trimming trailing whitespace
- Locating the word end
- Locating the word start
- Performing variable substitution
- 5. Expanding String Functionality Using Lists
- Introduction
- Creating a list
- Joining two lists
- Joining list elements
- Appending list elements
- Assigning list elements to variables
- Retrieving an element from a list
- Inserting elements into a list
- Determining the number of elements
- Getting a list element
- Repeating elements
- Replacing elements
- Reversing elements
- Searching a list
- Editing a list
- Sorting a list
- Splitting a string into a list
- 6. The Tcl Dictionary
- Introduction
- Creating a dictionary
- Appending to a dictionary
- Determining if a key exists
- Filtering a dictionary
- Searching a dictionary
- Getting a record
- Incrementing a value
- Getting the dictionary structure
- Getting a list of keys
- Appending to an existing record
- Merging two dictionaries
- Creating a blank dictionary structure
- Updating variables from a dictionary
- Determining the size of a dictionary
- Getting all records
- Assigning values
- 7. File Operations
- 8. Tk GUI Programming with Tcl/Tk
- 9. Configuring and Controlling Tk Widgets
- 10. Geometry Management
- 11. Using Tcl Built-in Dialog Windows
- 12. Creating and Managing Menus
- 13. Creating the Address Book Application
At some point, you may want to populate a list with a number of repeated elements. This may be for testing or various other reasons. To accomplish this, Tcl provides the lrepeat command. The syntax is as follows:
lrepeat number element1 element2 …
In the following example, we will use the lrepeat command to create a list of repeated characters. Return values from the commands are provided for clarity. Enter the following command:
% lrepeat 3 a
a a a
The lrepeat command creates a list of the size referenced in the number variable multiplied by the number of elements.
In the following example we will combine lrepeat commands to create multiple lists containing repeated characters. Return values from the commands are provided for clarity. Enter the following command:
% lrepeat 3 [lrepeat 3 0]
{0 0 0} {0 0 0} {0 0 0}
As you can see, by combining the lrepeat command we have created a list containing the same element repeated three times.
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