1. Chapter 8: Manipulating Strings
Programming with Microsoft Visual Basic .NET, Second Edition

2. String Manipulation Lesson A Objectives
Determine the number of characters contained in a string
Remove characters from a string
Determine whether a string begins or ends with one or more specific characters
Programming with Microsoft Visual Basic .NET, Second Edition

3. String Manipulation Lesson A Objectives (continued)
Access characters from the beginning, middle, and end of a string
Replace one or more characters in a string
Insert characters within a string
Search a string for one or more characters
Programming with Microsoft Visual Basic .NET, Second Edition

4. Manipulating Strings in Visual Basic .NET
Many times, an application needs to manipulate (process) string data
For example, an application might need to:
Verify that an inventory part number begins with a specific letter
Determine whether the last three characters in an employee number are valid
Programming with Microsoft Visual Basic .NET, Second Edition

5. Determining the Number of Characters Contained in a String
In many applications, it is necessary to determine the number of characters contained in a string
Use a string’s Length property to determine the number of characters contained in the string
Syntax of the Length property: string.Length
Programming with Microsoft Visual Basic .NET, Second Edition

6. Removing Characters from a String
TrimStart method
Remove one or more characters from the beginning of a string
Syntax: string.TrimStart([trimChars])
TrimEnd method
Remove one or more characters from the end of a string
Syntax: string.TrimEnd([trimChars])
Programming with Microsoft Visual Basic .NET, Second Edition

7. Removing Characters from a String (continued)
Trim method
Remove one or more characters from both the beginning and end of a string
Syntax: string.Trim([trimChars])
Programming with Microsoft Visual Basic .NET, Second Edition

8. Removing Characters from a String (continued)
string.Trim
Removes leading and trailing spaces
string.Trim(char)
Removes leading and trailing char
string.TrimStart
Removes leading spaces
string.TrimStart(char)
Removes leading char
string.TrimEnd
Removes trailing spaces
string.TrimEnd(char)
Removes trailing char
Programming with Microsoft Visual Basic .NET, Second Edition

9. The Remove Method
Use the Remove method to remove one or more characters located anywhere in a string
The Remove method returns a string with the appropriate characters removed
Syntax: string.Remove(startIndex, count)
Programming with Microsoft Visual Basic .NET, Second Edition

10. Determining Whether a String Begins or Ends with a Specific Sequence of Characters
StartsWith method
Determine whether a specific sequence of characters occurs at the beginning of a string
Syntax: string.StartsWith(subString)
EndsWith method
Determine whether a specific sequence of characters occurs at the end of a string
Syntax: string.EndsWith(subString)
Programming with Microsoft Visual Basic .NET, Second Edition

11. Accessing Characters Contained in a String
Use the Substring method to access any number of characters in a string
Syntax: string.Substring(startIndex[, count])
startIndex: the index of the first character you want to access in the string
count (optional): specifies the number of characters you want to access
Programming with Microsoft Visual Basic .NET, Second Edition

12. Replacing Characters in a String
Use Replace to replace a sequence of characters in a string with another sequence of characters
For example:
Replace area code “800” with area code “877” in a phone number
Replace the dashes in a Social Security number with the empty string
Programming with Microsoft Visual Basic .NET, Second Edition

13. Replacing Characters in a String (continued)
Syntax: string.Replace(oldValue, newValue)
oldValue is the sequence of characters that you want to replace in the string
newValue is the replacement characters
Programming with Microsoft Visual Basic .NET, Second Edition

14. The Mid Statement
Use the Mid statement to replace a specified number of characters in a string with characters from another string
Syntax: Mid(targetString, start [, count]) = replacementString
targetString: the string in which you want characters replaced
Programming with Microsoft Visual Basic .NET, Second Edition

15. The Mid Statement (continued)
replacementString: contains the replacement characters
start: the character position of the first character you want replaced in the targetString
count: the number of characters to replace in the targetString
Programming with Microsoft Visual Basic .NET, Second Edition

16. Inserting Characters at the Beginning and End of a String
Use the PadLeft and PadRight methods to pad a string with a character until the string is a specified length
PadLeft method pads the string on the left
Inserts the padded characters at the beginning of the string and right-aligns the characters in the string
Syntax: string.PadLeft(length[, character])
Programming with Microsoft Visual Basic .NET, Second Edition

17. Inserting Characters at the Beginning and End of a String (continued)
PadRight method pads the string on the right
Inserts the padded characters at the end of the string and left-aligns the characters in the string
Syntax: string.PadRight(length[, character])
Programming with Microsoft Visual Basic .NET, Second Edition

18. Inserting Characters within a String
Use the Insert method to insert characters within a string
For example: insert an employee’s middle initial within his or her name
Syntax: string.Insert(startIndex, value)
startIndex specifies where in the string you want the value inserted
Programming with Microsoft Visual Basic .NET, Second Edition

19. Searching a String
Use the IndexOf method to search a string to determine whether it contains a specific sequence of characters
Syntax: string.IndexOf(value[, startIndex])
value: the sequence of characters for which you are searching in the string
startIndex: the index of the character at which the search should begin
Programming with Microsoft Visual Basic .NET, Second Edition

20. Searching a String (continued)
For example:
Determine if the area code “312” appears in a phone number
Determine if the street name “Elm Street” appears in an address
Programming with Microsoft Visual Basic .NET, Second Edition

21. Searching a String (continued)
Figure 8-13: String manipulation techniques
Programming with Microsoft Visual Basic .NET, Second Edition

22. Searching a String (continued)
Figure 8-13: String manipulation techniques (continued)
Programming with Microsoft Visual Basic .NET, Second Edition

23. Using a Main Menu Control Lesson B Objectives
Add a main menu control to a form
Add menu elements to a main menu control
Assign access keys and shortcut keys to menu elements
Code a menu item’s Click event procedure
Programming with Microsoft Visual Basic .NET, Second Edition

24. Completing the Hangman Game Application’s User Interface
You will create a simplified version of the Hangman game for Mr. Mitchell, who teaches second grade at Hinsbrook School
In this lesson, you will:
Complete the application’s user interface
Begin coding the application
Programming with Microsoft Visual Basic .NET, Second Edition

25. Completing the Hangman Game Application’s User Interface (continued)
Figure 8-14: Partially completed interface for the Hangman Game application
Programming with Microsoft Visual Basic .NET, Second Edition

26. Adding a Main Menu Control to a Form
Use a main menu control to include one or more menus in an application
Each menu contains a menu title, which appears on the menu bar at the top of a Windows form
When you click a menu title, its corresponding menu opens and displays a list of options, called menu items
Programming with Microsoft Visual Basic .NET, Second Edition

27. Adding a Main Menu Control to a Form (continued)
The menu items can be commands, separator bars, or submenu titles
Clicking a command on a menu executes the command
Clicking a submenu title opens an additional menu of options
Programming with Microsoft Visual Basic .NET, Second Edition

28. Adding a Main Menu Control to a Form (continued)
Figure 8-15: Location of menu elements
Programming with Microsoft Visual Basic .NET, Second Edition

29. Adding a Main Menu Control to a Form (continued)
Each option on a submenu is referred to as a submenu item
The purpose of a separator bar is to visually group together the related items on a menu or submenu
Each menu element is considered an object and has a set of properties associated with it
The most commonly used properties for a menu element are the Name and Text properties
Programming with Microsoft Visual Basic .NET, Second Edition

30. Assigning Shortcut Keys
Appear to the right of a menu item
Allow you to select an item without opening the menu
You should assign shortcut keys only to commonly used menu items
Programming with Microsoft Visual Basic .NET, Second Edition

31. Assigning Shortcut Keys (continued)
Figure 8-19: Shortcut key displayed on the File menu
Programming with Microsoft Visual Basic .NET, Second Edition

32. Coding the Click Event Procedure for the Exit Menu Item
When the user clicks the Exit item on the File menu, the item’s Click event procedure should end the Hangman Game application
Programming with Microsoft Visual Basic .NET, Second Edition

33. Completing the Hangman Game Application Lesson C Objectives
Include the Substring method in a procedure
Include the Mid statement in a procedure
Include the IndexOf method in a procedure
Programming with Microsoft Visual Basic .NET, Second Edition

34. The Hangman Game Application
An application that two students can use to play a simplified version of the Hangman game on the computer
The application should allow one of the students to enter a five-letter word, and then allow the other student to guess the word, letter by letter
The game is over when the second student either guesses all of the letters in the word or makes 10 incorrect guesses, whichever comes first
Programming with Microsoft Visual Basic .NET, Second Edition

35. The Hangman Game Application (continued)
Figure 8-22: Hangman Game application’s user interface
Programming with Microsoft Visual Basic .NET, Second Edition

36. Coding the Click Event Procedure for the uiFileNewMenuItem
Each time the user wants to begin a new Hangman game, he or she will need to:
Click File on the application’s menu bar
Click New Game
Programming with Microsoft Visual Basic .NET, Second Edition

37. Coding the Click Event Procedure for the uiFileNewMenuItem (continued)
Figure 8-24: Pseudocode for the uiFileNewMenuItem’s Click event procedure
Programming with Microsoft Visual Basic .NET, Second Edition

38. Coding the Click Event Procedure for the uiFileNewMenuItem (continued)
Figure 8-24: Pseudocode for the uiFileNewMenuItem’s Click event procedure (continued)
Programming with Microsoft Visual Basic .NET, Second Edition

39. Summary
To determine the number of characters contained in a string, use the Length property in the following syntax: string.Length
To remove one or more characters from anywhere in a string, use the Remove method
Use the StartsWith method to determine whether a string begins with a specific sequence of characters
Programming with Microsoft Visual Basic .NET, Second Edition

40. Summary (continued)
Use the EndsWith method to determine whether a string ends with a specific sequence of characters
To access one or more characters contained in a string, use the Substring method
To insert characters within a string, use the Insert method
Programming with Microsoft Visual Basic .NET, Second Edition

41. Summary (continued)
To search a string to determine whether it contains a specific sequence of characters, use the IndexOf method
To add a main menu control to a form, use the MainMenu tool in the toolbox
To assign a shortcut key to a menu item, set the menu item’s Shortcut property
To replace a character in a string with another character, use the Mid statement
Programming with Microsoft Visual Basic .NET, Second Edition