<p>VB.NET Cheat Sheet By: Andrew Kiceniuk Unit 1: Computer Memory Computer Memory: Computers have two types of memory: </p><p>1. Permanent  ex: your hard drive  info stay on your computer even after the power is turned off.</p><p>2. Temporary  RAM (Random Access Memory)  this is the computers working memory, it allows programs to run, but all info saved in the RAM is lost when the computer’s power is turned off.</p><p>You can think of the computer’s RAM as being a collection of storage boxes. Sometimes your programs will need to save information to the computer’s RAM. That would be like putting the information into the storage box. Ex: 5 </p><p>Sometimes your programs will need to use information from the computer’s RAM. That would be like taking information out of the storage box. Ex: 5</p><p>These storage boxes are called memory locations. When we give a memory location a unique name we call it a variable.</p><p>Working With Variables: Working with a memory location involves three steps: 1) Declaring a variable (i.e. naming the memory location) 2) Initializing the variable (i.e. putting a value in the memory location) 3) Using the variable a. To complete of a calculation or b. To output an answer to a label</p><p>Let us look at each step: 1) Declaring a variable – requires a statement that has three parts: intNumberOfFeet</p><p>Statement Format: Dim preVariableName As DataType Declaration Example: Dim intNumberOfFeet As Integer</p><p>Dim - is a keyword to indicate that you want to name a memory location. VariableName – is the name you are giving the memory location. Is should be descriptive of the value to be saved in the memory location. - Notice that the variable name starts with a 3 letter, lowercase, prefix that describes the data type that the variable will hold. Data Type – This tells the computer what type of values will be saved into the memory location. The basic data types we will work with are: VB.NET Cheat Sheet By: Andrew Kiceniuk Unit 1: Computer Memory Data Type Value Held 3 Letter Prefix String “Text” str Integer numbers without decimals int Double numbers with decimals dbl Boolean True, 1, False, 0 bln Char A single keyboard chr character VB.NET Cheat Sheet By: Andrew Kiceniuk Unit 1: Computer Memory </p><p>2) Initializing a variable You can save a value to a memory location by using an assignment statement (as in you are assigning a value to the variable.) intNumberOfFeet</p><p>Statement Format: preVariableName = value Assignment Example: intNumberOfFeet = 5</p><p>You specify the variable name followed by the assignment operator (i.e. =), then the value. The value must match the data type specified in the variable declaration.</p><p>3) Using the variable You use variables either to:</p><p>1) complete a calculation Example: dblAnswer = intNumberOfFeet * 2.50 Computer reads it as: dblAnswer = 5* 2.50</p><p>2) display in a label Example: Me.lblAnswer.Text = dblAnswer Label displays: 12.50</p><p>When Do You Use Variables? There are two situations: 1.) To complete calculations – the result of a math calculation should be saved in a variable. Example: dblAnswer = intNumberOfFeet * 2.50</p><p>2.) To accept user input – whenever you have a TextBox on your form you will need a variable to save the value the user enters into it.</p><p>How to handle text input from a TextBox:</p><p>Statement Format: preVariableName = Me.TextBoxName.Text Example: strHomeTown = Me.txtHomeTown.Text</p><p>How to handle numeric input from a TextBox:</p><p>Statement Format: preVariableName = Val(Me.TextBoxName.Text) Example: intAge = Val(Me.txtPetsAge.Text)</p><p>Note: Everything entered into a TextBox is actually text. For example: The user input in the Kraken Kafe program is not recognized as a number, but rather as text (i.e. “25”). VB.NET Cheat Sheet By: Andrew Kiceniuk Unit 1: Computer Memory </p><p>We need to use the Val( ) method to convert the text value (“25”) into a numeric value (25).</p>