In this lesson we show how to use ASCII Codes to do Input Validation for Numbers and Strings. We then show a second method of Validation used for Phone Numbers and Email Addresses called "Regex Pattern Matching".
If you check the Lesson Contents further down on this page, it is essentially three lessons rolled into one. So we suggest you do the three lessons one at a time so that the workload is not too overwhelming.
Making use of ASCII Code Numbers makes checking for Letters or Numbers much more compact and simpler than trying to check for each of the letters of the alphabet separately; or having ten separate checks for the Digits 0 through 9.
The Step by Step Guide which is available below for this lesson shows exactly what needs to be done.
Also included are all of the Design Principles and Theory behind what is being done at each stage of input validation and String, Loop, and Substring Validation processing.
Note that the example Lesson Images shown on this web page are basic Printscreens, whereas the actual original Images are of perfect clarity and quality in the downloadable PDF Guide for this lesson.
LESSON OVERVIEW
This lesson consists of a Video Presentation where we cover the following THREE Validation Lessons:
- Lesson Intro and Overview
- Strings and Substrings Explanation and Examples
- ASCII Codes - What they are and Why we use them
LESSON A - KEY PRESS ASCII CODES VALIDATION
- Using the "KEY PRESS" event to do immediate checking as the User types each character into a Text Box
- How to Create the Key Press Event for a Text Box
- Program Code and Testing for the Key Press Subroutine
- Alternative Key Press Validation with TOOL TIP message
- Program Code for Tool Tip Message for Validation Errors
- Validating Key Press Number Values using ASCII Codes
- Program Code for Number Digits Validation
LESSON B - WHOLE STRING ASCII CODES VALIDATIONS
- What is Whole String Validation - Detailed Explanation
- Setting up the Screen Form for Customer ID
- Program Code for the Customer ID Validation
- Using the "Character Casing" Property to make Upper Case Letters
- Using the "Max Length" Property to limit Customer ID to 11 Characters
- Blank Text Box Program Crashing Problems
- Fixing the Program Crashing Problem with Existence Checking
- Checking that all 11 characters have been entered into Customer ID
- Quick Review of "Existence", "Type" and "Range" Validation Checking
- Testing the Validations for Blanks, Character 1 value, and Length.
- Checking that Characters 2 to 8 are Letters or Spaces (For Next Loop)
- Pseudocode of the For Next Loop Checking to work out the Logic
- Program Code for doing the Loop Checking of Customer ID
- Testing the Positions 1 to 7 Validation Checking
- Final Validation Check - 3 digit number ending on Customer ID
- Testing the 3 Digit Ending Validation
- Giving Update Success Message for Passing all 5 Validations
- Notes about being careful when validating People's Names
LESSON C - REGEX REGULAR EXPRESSIONS PATTERN MATCHING VALIDATIONS
- Using a Regex Pattern to Validate a Phone Number
- How to Code the Regex Pattern Matching
- Using Regex Pattern Validation for Email Addresses
- Adding an Email Text Box onto the Form
- Regex Program Code for Validating Email Addresses
- Testing the Email validation
- VB and C# Microsoft Regular Expressions for Modifying String Data
LESSON WRAP UP
- Why we have to learn many Different Programming Languages
- Full Programming Course Website
- Video Wrap Up and Outro
Watch the following YouTube Video Tutorial about ASCII and Regex Validations.
We recommend you use the RESOURCE MATERIALS available below
to follow along step by step with the Tutorial Video.
The YouTube Video is free to watch as many times as you want, and the Lesson Summary Guide, with a Step By Step Guide which includes full program code listing(s) are available at a small cost which can be paid for and downloaded using PayPal.
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Our students have found the Summary Guide to be far more useful than re-watching the Video, when it comes time for them to apply their newly acquired skills to Application Build tasks.
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