Outline Software and Programming Program Structure Tools for Designing Software Programming Languages Introduction to Visual Basic (VBA)

ENGR 112 Programming Languages

Types of Programming Procedural Strict sequence of processing steps Distinct start/stop points in program #include main() { printf("Content-type: text/html\n\n"); printf(" "); printf("Hello World!"); printf(" "); }

Types of Programming Event-Driven Waits for an “event” to trigger program execution Modular programming No start/stop point in program

Types of Programming Event-Driven

Private Sub cmbDates_Click() Me.txtSSNScanned.SetFocus Call scanSSN End Sub Private Sub cmdEndProgram_Click() If endProgram Then End Else endProgram = False End If End Sub Private Sub txtSSNScanned_GotFocus() If Me.cmbDates.Text = "" Then MsgBox ("You need to enter a date!") Me.cmbDates.SetFocus Exit Sub End If End Sub Procedure #2 Procedure #3 Procedure #1

Programming Languages Assembly Language Fast and most efficient Very difficult to program in Basic Beginner’s All-purpose Symbolic Instruction Code Easy to use Lacks total control

Programming Languages Fortran FORmula TRANslator Great for mathematical programming Not good for other uses, e.g. graphics C and C++ Powerful tools Harder to use/learn than BASIC Can do anything

Programming Languages Visual Basic Develop windows programs easily Powerful tool Not as much control as Visual C VBA (Visual Basic for Applications) Visual C and C++ Develop windows applications Not easy to learn

VBA Macro Programming VBA is a general purpose programming language that comes standard with Excel or Office. Using VBA with Excel, powerful engineering analysis tools can be developed quickly and with minimum cost. VBA can be used for many engineering tasks communicating with engineering databases analyzing engineering data automating worksheet construction engineering modeling and simulation creating charts and engineering wizards (i.e. dialog boxes) creating GUI's

Advantages of VBA Programmer does not need to be an expert Windows programmer Programmer creates GUI and defines what happens when user interacts with it Events are generated Push a button, move mouse, etc. This is called event-driven programming

Visual Basic Overview Objects Events Numbers Strings Variables Operators

Elements of a Visual Basic Objects & Events Label Text box Picture box (text) Picture box (image) Command button

Object Properties The most important properties (at least for the purpose of this course) are: Name (object’s name – important!!) Caption (text to be displayed by the object) Font (what the text looks like) Visible (how it links to other applications)

Objects With Names lblEngr112 txtInputA, txtInputB picResults picCOE cmdAddButton

Visual Basic Events Change initiated by user Load a Form Click on a button Mouse down/up, Mouse drag Key down, key press, etc. Causes an event procedure (subprogram) to execute

Elements of Visual Basic Data Constants (data that does not change) Numbers (e.g., ) Strings (e.g., “this is a string”) Variables (names of data holders) Numbers Strings Operators Arithmetic (+, -, *, /, etc.) String (&)

Visual Basic Integers Sequence of digits with no Commas Decimal points Negative numbers preceded by ‘-’ Positive numbers optionally preceded by ‘+’

Single Precision Real Numbers Standard Representation Integer (whole number) portion Decimal point Unsigned integer (fractional) portion

Visual Basic Strings String: Sequence of characters (a, b, c,..., 0, 1, 2,..., ~, !,...) treated as a unit Enclosed in double quotes in VB statement “this is a string” “John Smith” “ ” “a + b = “

Visual Basic Variables Variable Symbolic name for data value Name of data “holder” Name of a location in random access memory Variable names rules Must begin with a letter May contain only letters, digits, and underscores (_) Up to 255 characters long

Variable Names a, b, c,..., x, y, z distance, speed, time, average rateOfIncrease, startingTime, hoursPerWeek rate_of_increase, starting_time, hours_per_week

Declaring Variable Types Two options Implicit declaration Explicit declaration Dim name As String Dim count As Integer Dim average As Single Dim nextItem As Variant Explicit declaration is always preferable!!

VB Arithmetic Operators Addition (+) a + b Subtraction (-) a - b Multiplication (*) a * b Division (/) a / b Exponentiation (^) a ^ b

Arithmetic Order of Evaluation 1. Exponentiation (R - L) 2. Multiplication & division (L-R) 3. Addition & subtraction (L-R)

Examples of Evaluation (1) * *

Converting Formulas to VB 1 a + b 1c1c 1d1d efef ghgh (1.0 / (a + b)) ^ 2 / ((1.0 / c / d) * (e / f - g / h))

String Operator Concatenation (&) “good” & “bye” “goodbye”