1. Chapter 8: Manipulating Strings
Programming with Microsoft Visual Basic 2005, Third Edition

2. String Manipulation Lesson A Objectives
Determine the number of characters contained in a string
Remove characters from a string
Replace one or more characters in a string
Insert characters within a string
Programming with Microsoft Visual Basic 2005, Third Edition

3. String Manipulation Lesson A Objectives (continued)
Search a string for one or more characters
Access characters contained in a string
Compare strings
Programming with Microsoft Visual Basic 2005, Third Edition

4. Manipulating Strings in Visual Basic 2005
Applications often need to manipulate string data
Two scenarios involving string manipulation
Determining the first letter of an inventory part id
Validating last three characters in an employee id
Programming with Microsoft Visual Basic 2005, Third Edition

5. Determining the Number of Characters Contained in a String
Length property
Stores number of characters contained in a string
Syntax of the Length property: string.Length
Using Length property to validate length of ZIP code
Dim numChars As Integer numChars = Me.xZipTextBox.Text.Length
Length of entered ZIP code is assigned to numChars
Programming with Microsoft Visual Basic 2005, Third Edition

6. Removing Characters from a String
TrimStart method
Removes one or more characters from start of string
TrimEnd method
Removes one or more characters from end of string
Trim method
Removes one or more characters from both ends
All methods take optional trimChars argument
Programming with Microsoft Visual Basic 2005, Third Edition

7. Removing Characters from a String (continued)
Figure 8-4: Syntax, purpose, and examples of the TrimStart, TrimEnd, and Trim methods (continued)
Programming with Microsoft Visual Basic 2005, Third Edition

8. Removing Characters from a String (continued)
Figure 8-4: Syntax, purpose, and examples of the TrimStart, TrimEnd, and Trim methods
Programming with Microsoft Visual Basic 2005, Third Edition

9. The Remove Method Remove method
Removes one or more characters anywhere in string
Returns a string with appropriate characters removed
Syntax: string.Remove(startIndex, count)
Example
Dim fullName As String = "John Cober“ Me.xNameTextBox.Text = fullName.Remove(0, 5)
Assigns “Cober” to xNameTextBox’s Text property
Programming with Microsoft Visual Basic 2005, Third Edition

10. Replacing Characters in a String
Replace method
Replace one sequence of characters with another
Example: replace area code “800” with “877”
Replace syntax: string.Replace(oldValue, newValue)
oldValue: sequence of characters in string to replace
newValue: the replacement characters
Replace method returns a string with newValue
Programming with Microsoft Visual Basic 2005, Third Edition

11. Replacing Characters in a String (continued)
Figure 8-6: Syntax, purpose, and examples of the Replace method
Programming with Microsoft Visual Basic 2005, Third Edition

12. The Mid Statement Mid statement
Replaces set of characters with another string
Syntax: Mid(targetString, start [, count]) = replacementString
targetString: string targeted for character replacement
replacementString: contains replacement characters
start: position of first character of the targetString
count: number of characters to replace in targetString
Programming with Microsoft Visual Basic 2005, Third Edition

13. The Mid Statement (continued)
Figure 8-7: Syntax, purpose, and examples of the Mid statement
Programming with Microsoft Visual Basic 2005, Third Edition

14. Inserting Characters at the Beginning and End of a String
PadLeft method
Inserts padded characters at start of string
Right-aligns the characters within the string
Syntax: string.PadLeft(length[, character])
PadRight method
Inserts padded characters at the end of the string
Left-aligns the characters within the string
Syntax: string.PadRight(length[, character])
Programming with Microsoft Visual Basic 2005, Third Edition

15. The Insert Method Insert method
Inserts characters anywhere within a string
Example: insert middle initial within employee name
Syntax: string.Insert(startIndex, value)
startIndex specifies position in string where value will be inserted
Programming with Microsoft Visual Basic 2005, Third Edition

16. The Insert Method (continued)
Figure 8-9: Syntax, purpose, and examples of the Insert method
Programming with Microsoft Visual Basic 2005, Third Edition

17. Searching a String StartsWith method EndsWith method
Determine if sequence occurs at start of string
Syntax: string.StartsWith(subString)
EndsWith method
Determine if sequence occurs at the end of a string
Syntax: string.EndsWith(subString)
Both methods return Boolean value (True or False)
Programming with Microsoft Visual Basic 2005, Third Edition

18. The Contains Method Contains method
Determines if string contains a character sequence
Returns a Boolean value (True or False)
Contains syntax: string.Contains(subString)
subString is the sequence to search for in string
Example
Dim phone As String = "(312) 999–9999“ If phone.Contains("(312)") Then
Condition will evaluate to True
Programming with Microsoft Visual Basic 2005, Third Edition

19. The IndexOf Method IndexOf method
Determine if string contains a character sequence
Returns integer specifying start position of substring
If substring is not found, method returns -1
Syntax: string.IndexOf(value[, startIndex])
value: sequence of characters to search in the string
startIndex: index of character at which search begins
Programming with Microsoft Visual Basic 2005, Third Edition

20. The IndexOf Method (continued)
Figure 8-12: Syntax, purpose, and examples of the IndexOf method (continued)
Programming with Microsoft Visual Basic 2005, Third Edition

21. The IndexOf Method (continued)
Figure 8-12: Syntax, purpose, and examples of the IndexOf method
Programming with Microsoft Visual Basic 2005, Third Edition

22. Accessing Characters Contained in a String
Substring method
Used to access any number of characters in a string
Returns string with specified number of characters
Syntax: string.Substring(startIndex[, count])
startIndex: index of first character to access in string
count: specifies number of characters to access
Programming with Microsoft Visual Basic 2005, Third Edition

23. Accessing Characters Contained in a String (continued)
Figure 8-13: Syntax, purpose, and examples of the Substring method
Programming with Microsoft Visual Basic 2005, Third Edition

24. Comparing Strings String.Compare method
Used to compare two strings
Supplements the comparison operators
Returns three values: 1, 0, and -1
Syntax: String.Compare(string1,string2[,ignoreCase])
string1 and string2 are two strings to compare
ignoreCase: Boolean argument set to True or False
Word sort rules are used to compare strings
Numbers < lowercase letters < uppercase letters
Programming with Microsoft Visual Basic 2005, Third Edition

25. Comparing Strings (continued)
Figure 8-14: Syntax, purpose, and examples of the String.Compare method
Programming with Microsoft Visual Basic 2005, Third Edition

26. Summary – Lesson A Determine string length with Length property
Methods for removing characters: Trim, TrimStart, TrimEnd, and Remove
Replace characters with Replace method and Mid statement
Pad strings with PadLeft and PadRight methods
Insert characters in a string with the Insert method
Programming with Microsoft Visual Basic 2005, Third Edition

27. Summary – Lesson A (continued)
Methods determining presence of a substring: StartsWith, EndsWith, Contains, and IndexOf
Access one or more characters in a string using the Substring method
Compare strings using String.Compare method, Like operator, or comparison operators
Programming with Microsoft Visual Basic 2005, Third Edition

28. Adding a Menu to a Form Lesson B Objectives
Include a MenuStrip control on a form
Add elements to a menu
Assign access keys to menu elements
Assign shortcut keys to commonly used menu items
Code a menu item’s Click event procedure
Programming with Microsoft Visual Basic 2005, Third Edition

29. Completing the Hangman Game Application’s User Interface
Objective: create simplified version of Hangman
Lesson tasks
Complete the application’s user interface
Begin coding the application
Programming with Microsoft Visual Basic 2005, Third Edition

30. Completing the Hangman Game Application’s User Interface (continued)
Figure 8-16: Partially completed interface for the Hangman Game application
Programming with Microsoft Visual Basic 2005, Third Edition

31. Creating Menus MenuStrip control: basis for adding menus
MenuStrip tool: instantiates MenuStrip control
Menu title: appears on menu bar at top of form
Menu items
Commands, submenu items, or separator bars
Clicking a command on the menu executes it
Clicking a submenu item opens an additional menu
Programming with Microsoft Visual Basic 2005, Third Edition

32. Creating Menus (continued)
Figure 8-17: Location of menu elements
Programming with Microsoft Visual Basic 2005, Third Edition

33. Creating Menus (continued)
Menu title captions should be one word only
Menu item captions can be from one to three words
Assign unique access keys to menu titles and items
Follow Windows menu conventions
Ellipsis (…) after item caption indicates need for input
File menu should be first menu on menu bar
Cut, Copy, Paste should appear on an Edit menu
Programming with Microsoft Visual Basic 2005, Third Edition

34. Assigning Shortcut Keys to Menu Items
Appear to the right of a menu item
Allow you to select an item without opening a menu
Example: Ctrl + S executes Save in MS Word
Assign shortcut keys to commonly used menu items
Programming with Microsoft Visual Basic 2005, Third Edition

35. Assigning Shortcut Keys (continued)
Figure 8-23: Shortcut key appears next to the New Game menu item
Programming with Microsoft Visual Basic 2005, Third Edition

36. Coding the Exit Option’s Click Event Procedure
How to end the Hangman Game application
User clicks the Exit item on the File menu
Exit item’s Click event procedure calls Me.close()
Programming with Microsoft Visual Basic 2005, Third Edition

37. Summary – Lesson B MenuStrip control is the basis for a menu
Menu items: commands, submenu items, separator bars
Assign a unique access key to each menu element
Assign shortcut keys to commonly used menu items
Follow the Windows standard when creating menus
Programming with Microsoft Visual Basic 2005, Third Edition

38. Completing the Hangman Game Application Lesson C Objectives
Include the Length property in a procedure
Include the Substring method in a procedure
Include the Mid statement in a procedure
Include the Contains method in a procedure
Programming with Microsoft Visual Basic 2005, Third Edition

39. The Hangman Game Application
Application requirements
Allow one student to enter a five-letter word
Allow another student to guess word, letter by letter
Two events can end the game
Second student guesses all of the letters in the word
Second student makes 10 incorrect guesses
Programming with Microsoft Visual Basic 2005, Third Edition

40. Coding the xFileNewMenuItem’s Click Event Procedure
Two ways to begin a new Hangman game
Click File on the menu bar, then click New Game
Press Ctrl + N
Programming with Microsoft Visual Basic 2005, Third Edition

41. Coding the xFileNewMenuItem’s Click Event Procedure (continued)
Figure 8-26: Pseudocode for the xFileNewMenuItem’s Click event procedure (continued)
Programming with Microsoft Visual Basic 2005, Third Edition

42. Coding the xFileNewMenuItem’s Click Event Procedure (continued)
Figure 8-26: Pseudocode for the xFileNewMenuItem’s Click event procedure
Programming with Microsoft Visual Basic 2005, Third Edition

43. Coding the xFileNewMenuItem’s Click Event Procedure (continued)
Figure 8-33: Result of guessing the word
Programming with Microsoft Visual Basic 2005, Third Edition

44. Summary – Lesson C
Hangman application uses various methods to manipulate strings
Substring method: used to access characters in a string
Mid statement: replaces one character with another
Contains method: determines whether a specific character is within a string
Programming with Microsoft Visual Basic 2005, Third Edition