Book Image

Tcl/Tk 8.5 Programming Cookbook

Book Image

Tcl/Tk 8.5 Programming Cookbook

Overview of this book

With Tcl/Tk, you can create full-featured cross-platform applications in a simple and easy-to-understand way without any expensive development package; the only tools required are a simple text editor and your imagination. This practical cookbook will help you to efficiently interact with editors, debuggers, and shell type interactive programs using Tcl/Tk 8. This cookbook will comprehensively guide you through practical implementation of Tcl/Tk 8.5 commands and tools. This book will take you through all the steps needed to become a productive programmer in Tcl/Tk 8. Right from guiding you through the basics to creating a stand-alone application, it provides complete explanation of all the steps along with handy tips and tricks. The book begins with an introduction to the Tcl shell, syntax, variables, and programming best practices in the language. It then explores procedures and the flow of events with control constructs followed by advanced error trapping and recovery. From Chapter 4, a detailed study of string expressions and handling enables you to handle various string functions and use lists to expand the string functionality. The book then discusses in-depth the Tcl Dictionary and how to utilize it to store and retrieve data. File operations and Tk GUI handling are covered extensively along with a developing a real-world address book application to practice the concepts learned.
Table of Contents (20 chapters)
Tcl/Tk 8.5 Programming Cookbook
About the Author
About the Reviewers

Comparing strings

In any of the programs, string comparison is critical for many reasons. To perform string comparison, Tcl provides two keywords for use with the string command—compare and equal. The syntax for the first keyword compare is as follows:

string compare nocase length string1 string2

When invoked with the compare keyword, the string command performs a character-by-character comparison of the strings passed in string1 and string2.

The string command accepts two switches as mentioned here:

  • -nocase

    Strings are compared in a case-insensitive manner

  • -length

    Instructs the interpreter to perform the comparison only on the first length characters

Getting ready

To complete the following example, we will need to create a Tcl script file in your working directory. Open the text editor of your choice and follow the given instructions.

How to do it…

In the following example, we will create a Tcl script to accept a string value to compare against a static value. In this method, you can see...