Tutorial 11

1
Tutorial 11 12

• INFS308
• Spring2006

2
Overview

• Some String processing functions
• Select Case Processing

3
Substring Hints

• String Processing
• String.length gives length of strings aka Len()
• String.Substring(start, length) gives part of
  string identified
  
• Given textbox1.text has the value Happy
• textbox1.text.length 5 aka
  Len(textbox1.text)
  
• Substring(start, length)
• Textbox1.text.Substring(0, 1) H
• Textbox1.text.Substring(2, 3) ppy

4
In Class Exercise

• Write a program to reverse the contents of a text
  box and place it in a second. Now, determine if
  the contents of the first text box is a
  palindrome. A palindrome is a series of text that
  is the same forwards and backwards. So, madam
  is a palindrome, while happy is not. The string
  madam im adam is also considered a palindrome.
  This means that you must remove the spaces before
  comparing. Finally, Madam Im Adam is also a
  palindrome, which means that you must allow for
  upper case letters.

5
In Class Exercise
6
In Class Exercise

• You must use a counted loop to go through the
  textboxes.
  
• Hints
• Do the program in steps 1.) reverse the textbox
  1 contents to textbox 2.) check for madam as a
  palindrome 3.) remove the spaces and check for
  madam im adam as a palindrome 4.) now check
  for Madam Im Adam.
• The Len (string) function returns the length of
  the string
  
• The substring method of an object.Text reference
  can be used to obtain a substring from the
  contents of the object.Text.
  
• Given that txtIn has the text madam, the
  reference txtIn.Text.Substring(0, 1) evaluates to
  m, the reference txtIn.Text.Substring(2, 1)
  evaluates to d, the reference
  txtIn.Text.Substring(1, 2) evaluates to ad
• Think about how you would remove the spaces.

7
Case Flowchart

• Assume that you want to develop a program that
  looks at a coin and adds the value of that coin
  to a total.

Dime ?
Add .10
Penny ?
Add .01
Nickel ?
Add .05
Qtr ?
Add .25
8
If Statement

• Assume that you want to develop a program that
  looks at a coin and adds the value of that coin
  to a total.
  
• IF (coin dime) THEN
• Total total .10
• ELSEIF (coin penny) THEN
• Total Total .01
• ELSEIF (coin nickel) THEN
• Total Total .05
• ELSEIF (coin quarter) THEN
• Total Total .25
• ENDIF

9
Case Flowchart

• Select Case coin
• Case dime
• total total 10
• Case penny
• total total 1
• Case nickel
• total total 5
• Case quarter
• total total 25
• Case Else
• total total 0
• End Select

Dime ?
Add .10
Penny ?
Add .01
Nickel ?
Add .05
Qtr ?
Add .25
10
Select Case Statement

• Special If statement with ElseIf
• Evaluates expression then looks for case matching
  expression
  
• If found, it executes first case that matches and
  ends Select Case statement
  
• Format
• Select Case expression
• Case expressionlist1
• block1
• Case expressionlist2
• block2
• Case expressionlistN
• blockN
• Case Else
• Else block
• End Select

11
Summary

• Strings can be processed like listboxes they are
  a structure with each letter or character as an
  element.
  
• Select Case
• Substitutes for IF THEN ELSEIF construct
• Executes first condition that is true and exits
  to END SELECT