CSCI13003A

1
Lecture-12 (7.1-7.9)

• CSCI130-03A
• Instructor Dr. Imad Rahal

2
Coding Standards

• Every object used MUST be renamed including the
  form (s) using the following rules
• Form ?frmFormName
• frmTemperature
• Textbox ? txtTextBoxName
• txtInput
• Label ? lblLabelName
• lblDescribeInput
• Button ? cmdButtonName
• cmdButtonName
• PictureBox ? picPictureBoxName
• picOutput

3
Summary

• Must use Option Explicit
• Declare all variables
• No need for Val function
• 2s Complement
• Integer or Long
• Floating-point
• Single or Double
• Boolean
• ASCII Data
• String

4
Summary

• Start Subs by declaring variables
• What is a variable?
• Letters and numbers (some signs)
• Initialize
• 0 for numbers
• Empty for String
• False for Boolean
• Variable scope
• In Sub ? local
• Outside ? Global

5
Numeric Functions

• Program calculate the roots of a quadratic
  equation given a, b and c

• Sqr(X)
• Square root
• Sqr(2)
• Int(X)
• Sqr(2.1234)
• Round(X)
• To the nearest integer
• Sqr(2.45)
• Abs(X)
• Abs(-34)
• Log(X)
• Log(4)
• Enter a real number

• Private Sub Quadraticbutton_Click()
• Dim A As Integer, B As Integer, C As Integer
• Dim R1 As Double, R2 As Double
• A Abox.Text
• B Bbox.Text
• C Cbox.Text
• R1 (-BSqr(B2-4AC))/(2A)
• R2 (-B-Sqr(B2-4AC))/(2A)
• Results.Print Roots areR1R2
• End Sub

6
String Functions

• Used for string variables or appear in print
  functions
• Substring functions
• Left (Str, Count)
• Returns substring from the left side of a string
• Requires a count (goes left)
• Right (Str, Count)
• Returns substring from the right side of a string
• Requires a count (goes right)
• Mid (Str, StartPoint, Count)
• Returns substring from the middle of a string
• Requires a starting point and a count (to the
  starting points right)

7
String Functions

• InStr(S1,S2)
• Searches for string S2 in S1
• Returns the first position it is found in
• A Instr(St. Johns, .) ?
• Len(S)
• Returns the number of characters in S
• Len(A) ?
• Trim removes spaces from both ends of a string
• Concatenation is done with
• A College of Saint Benedict
• B Saint Johns University
• C AB ?

8
String Functions

• College of Saint BenedictSaint Johns University
• No space
• How can we add one?
• To any of the concatenated strings
• On its own
• College of Saint BenedictSaint Johns University?

9
String Functions

• Program to input first, middle Initial and last
  name
• Returns username as first letter of first name,
  middle initial and then last name (no spaces
  between them) in lower case

Private Sub Usernamebutton_Click() Dim n As
String Dim sp As Integer Dim first As String,
middle As String, last as String Dim username As
String Results.Cls n Namebox.Text sp
InStr(n, ) first Left(n, sp-1) middle
Mid(n, sp1,1) last Right(n, Len(n)-(sp2))
skip middle initial and space username
Left(first,1) middle Last Results.Print
Your username is LCase(username) End Sub
10
Input Output

• Spacing
• (semicolon)
• Combines numbers and strings on Prints
• 1 space after a number for readability
• 1 space for the sign (if any)
• Non for strings
• Try where Answer is a number and then String
• Results.Print The answer isAnswer
• , (comma)
• Every picture box is divided into 14-space print
  zones
• Jumps to the next zone (does not jump 14 spaces
  necessarily!)
• From its current location (its current 14-space
  zone)
• Results.Print 5,30,2

11
Input Output

• Tab function Tab(X)
• Followed by a (automatically inserted by VB)
• leaves X spaces from start
• Pushes any overlap to new lines
• Results.Print Tab(2) Hi!
• Results.Print Tab(2) Hi! Tab(2) Bi!
• What should the second 2 be to print on the same
  line

12
Input Output

• FormatCurrency(x,y) --- y is 2 by default
• x is the number to be formatted
• y is the number of digits allowed after the
  decimal point (rounding)
• Extra 0s are appended
• Adds a sign and commas if needed
• FormatCurrency(1234.234,2) 1,234.23
• FormatCurrency(1234.2,2) ?
• FormatPercent(x,y) --- y is 2 by default
• x is the decimal number to be formatted
• y is the number of digits allowed after the
  decimal point (rounding)
• Extra 0s are appended
• FormatPercent(0.5235, 1) 52.4
• FormatNumber(x,y) --- y is 2 by default
• Rounds x to the nearest number of digits after
  the decimal point specified by y
• FormatPercent(0.5235) 0.52
• FormatPercent(0.5235,3) 0.54

13
Input Output

• Message Boxes
• For output specially in situations of errors
• Other than textboxes and pictureboxes
• MsgBox prompt, ,title
• MsgBox Sorry but you must enter a positive
  number , , Error

14
Input Output

• Input Boxes
• Other than textboxes
• Good for small amount of input (form full of
  textboxes is not nice)
• X Inputbox( prompt, title)
• The input is assigned to variable X when the use
  hits OK
• A Inputbox(Enter an exam score,Exam 1)