Download Variables

CS 0004 –Lecture 3
Jan 10, 2011
Roxana Gheorghiu
VBA Controls and Variables
 Controls (components) = building block of a GUI
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Labels
Textboxes
Buttons
Check boxes
Radio buttons
 Variables = identifiers used in a program to hold some data
◦ Algebra: x=5; y=x*x;
◦ VBA:
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Dim x as Integer
Dim y as Integer
x =5
y =2*x
Variable Types
 Each type is design to store a particular type of
data
 Possible data types:
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Integer: -1000, 10, 0, 20000
Double: -10.5, 0.0, -200.3456
String : “ this is a string”, “anotherOne”
Date
…
 2-phase process
 Declaration
 Assignment of value (usage)
Create the container
 Declarations
 Phase that creates a variable
 Dim varName as Type
 Dim name as String or Dim x as Integer or …
 Rules for variable names:
 Can only use letters, numbers and underscore (_)
Price
 Must start with a letter or
underscore
 Cannot have spaces As
 Cannot use special characters
Integer
 Cannot be a keyword
Fill the container
 Assignment of value =gives the variable a value
 By assigning a value
 myName =“Roxana”; shoesPrice =30
 By assigning a value from another variable
 newAddress =oldAddress
 By using arithmetic operations
Price
As
Integer
Fill the container
 Assignment of value =gives the variable a value
 By assigning a value
 myName =“Roxana”; shoesPrice =30
 By assigning a value from another variable
 newAddress =oldAddress
 By using arithmetic operations
Arithmetic operations
 Addition: +
◦ x = 5+5; x=y+5
 Subtraction: -
◦ x = 100 -2; myBudget =mySalary -2000
 Division: /
◦ z = X/2
 Multiplication: *
◦ x = 10*y
◦ y = 2*5;
 Exponentiation: ^
◦ y = x^2
◦ z = 2^3
Arithmetic Shorthand
 Incrementing Numbers
Dim x as Integer
x =x+1
OR
x+ =1
 Decrementing Numbers
Dim y as Integer
y=y-1
OR
y-=1
More Arithmetic Operations
 Rounding
 Math.Round(number, precision)
 Math.Round(2.182 , 1) =2.2
 Math.Round(2.182) =2.0
 Modulo =the reminder after you divide the two
numbers
 5 Mod 3 =2
 21 Mod 2 =1
 Square Root
 Math.Sqrt(9)
Compute the perimeter
 Write a program that :
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Allows a user to give two values: length and width
reads the values of length and the width
computes the perimeter when Calc button is pressed.
displays this value on the screen.
exits when Exit button is pressed