CS 0004 –Lecture 3 Jan 10, 2011 Roxana Gheorghiu

 Controls (components) = building block of a GUI ◦ Labels ◦ Textboxes ◦ Buttons ◦ Check boxes ◦ Radio buttons  Variables = identifiers used in a program to hold some data ◦ Algebra: x=5; y=x*x; ◦ VBA:  Dim x as Integer  Dim y as Integer  x =5  y =2*x VBA Controls and Variables

Each type is design to store a particular type of data Possible data types: Integer: -1000, 10, 0, Double: -10.5, 0.0, String : “ this is a string”, “anotherOne” Date … 2-phase process Declaration Assignment of value (usage) Variable Types

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 (_) Must start with a letter or underscore Cannot have spaces Cannot use special characters Cannot be a keyword 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 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

 Addition: + ◦ x = 5+5; x=y+5  Subtraction: - ◦ x = ; myBudget =mySalary  Division: / ◦ z = X/2  Multiplication: * ◦ x = 10*y ◦ y = 2*5;  Exponentiation: ^ ◦ y = x^2 ◦ z = 2^3 Arithmetic operations

Incrementing Numbers Dim x as Integer x =x+1ORx+ =1 Decrementing Numbers Dim y as Integer y=y-1ORy-=1 Arithmetic Shorthand

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) More Arithmetic Operations

Compute the perimeter Write a program that : 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