Microsoft Visual Basic 2005 BASICS Lesson 4 Mathematical Operators

Microsoft Visual Basic 2005 BASICS2 Objectives Describe the purpose of operators and how calculations are performed in Visual Basic. Create label controls. Use the addition and assignment operators.

Microsoft Visual Basic 2005 BASICS3 Objectives (cont.) Use text boxes to get data from the user and use the Val function to extract a numeric value from a text box. Split code statements among the lines in the code window. Use the subtraction operator. Use unary minus.

Microsoft Visual Basic 2005 BASICS4 Objectives (cont.) Use the multiplication and division operators with the Fix function to remove the fractional portion of numbers. Perform integer division and use the modulus operator.

Microsoft Visual Basic 2005 BASICS5 Performing Calculations in Visual Basic Visual Basic allows you to use mathematical equations in your programs. Operators  Symbols that perform specific operations in Visual Basic statements

Microsoft Visual Basic 2005 BASICS6 Performing Calculations in Visual Basic (cont.)

Microsoft Visual Basic 2005 BASICS7 Creating Label Controls Label control  Used to place text in a form Sometimes a label is used to identify a text box.  May also be used to add a title or message to a form

Microsoft Visual Basic 2005 BASICS8 Creating Label Controls (cont.) Labels can also be used to provide output.  To provide output, you write code for the desired calculation.

Microsoft Visual Basic 2005 BASICS9 Using the Addition and Assignment Operators The addition operator (+) and the assignment operator (=)  Perform just as you would expect The term “hard-coded”  Information entered directly into the code  Cannot change while the program runs Literals  Values keyed directly into source code

Microsoft Visual Basic 2005 BASICS10 Using the Addition and Assignment Operators (cont.)

Microsoft Visual Basic 2005 BASICS11 Using Text Boxes and the Val Function Text boxes  Fields placed on dialog boxes and in other windows  Allow the user to enter a value The Text property of a text box  Specifies what text will appear on the text box

Microsoft Visual Basic 2005 BASICS12 Using Text Boxes and the Val Function (cont.)

Microsoft Visual Basic 2005 BASICS13 How Text Differs from Numeric Data Text  Can include letters, symbols, and numbers  Treated differently than strictly numeric information Numbers in a text box must be converted to a true numeric value b efore they can be used in a calculation.

Microsoft Visual Basic 2005 BASICS14 Using the Val Function Val function  Takes numbers that are in text format  Returns a numeric value that can be used in calculations Syntax example  lblTotal.Text = Val(txtPrice.Text) + Val(txtSalesTax.Text)

Microsoft Visual Basic 2005 BASICS15 Splitting Code Statements among Lines Visual Basic provides a way to split a line of code among two or more lines. Line-continuation character  Within a line of code, you can key the underscore.  Tells the compiler to skip the next line  Treats the text there as if it were a part of the same line

Microsoft Visual Basic 2005 BASICS16 Splitting Code Statements among Lines (cont.)

Microsoft Visual Basic 2005 BASICS17 Splitting Code Statements among Lines (cont.)

Microsoft Visual Basic 2005 BASICS18 Splitting Code Statements among Lines (cont.)

Microsoft Visual Basic 2005 BASICS19 Using the Subtraction Operator The subtraction operator  Subtracts the value to the right of the operator from the value to the left of the operator

Microsoft Visual Basic 2005 BASICS20 Using the Subtraction Operator (cont.)

Microsoft Visual Basic 2005 BASICS21 Using the Subtraction Operator (cont.)

Microsoft Visual Basic 2005 BASICS22 Using Unary Minus Unary minus operator  Performs negation Making a positive value negative Or making a negative value positive The addition operator can be used as a unary plus.

Microsoft Visual Basic 2005 BASICS23 Using Unary Minus (cont.)

Microsoft Visual Basic 2005 BASICS24 Using Fix Truncation  Drops the fractional part of a number Fix function  Returns a truncated whole number

Microsoft Visual Basic 2005 BASICS25 Using Fix (cont.)

Microsoft Visual Basic 2005 BASICS26 Performing Integer Division and Using the Modulus Operator Integers are whole numbers. Visual Basic provides two special operations  Integer division  Modulus

Microsoft Visual Basic 2005 BASICS27 Performing Integer Division Integer division  Returns only the whole number portion of the division of integers Integer division is performed using the backslash (\).

Microsoft Visual Basic 2005 BASICS28 Performing Integer Division (cont.)

Microsoft Visual Basic 2005 BASICS29 Performing Integer Division (cont.)

Microsoft Visual Basic 2005 BASICS30 Using the Modulus Operator Modulus returns the remainder of integer division. The modulus operator is (Mod).

Microsoft Visual Basic 2005 BASICS31 Summary Visual Basic allows you to use mathematical equations in your programs. Operators are symbols that perform specific operations in Visual Basic statements. The addition operator (+) adds values.

Microsoft Visual Basic 2005 BASICS32 Summary (cont.) The assignment operator (=) assigns the result of the expression on the right of the operator to the item to the left of the operator. The subtraction operator (–) subtracts the value to the right of the operator from the value to the left of the operator. It can be used to perform negation and is then called the unary minus.

Microsoft Visual Basic 2005 BASICS33 Summary (cont.) Values keyed directly into Visual Basic code are called hard-coded values or literals. Text boxes are the fields placed on dialog boxes and in other windows that allow the user to enter a value.

Microsoft Visual Basic 2005 BASICS34 Summary (cont.) The numbers in a text box are considered to be text characters. To use the numbers as actual values in a calculation, the Val function must be used to convert the numeric text to a numeric value.

Microsoft Visual Basic 2005 BASICS35 Summary (cont.) When a line of code is long, you can split the code into two lines in the Code window by keying an underscore at the end of the line and continuing the statement on the next line. The underscore is called the line- continuation character.

Microsoft Visual Basic 2005 BASICS36 Summary (cont.) Placing an apostrophe in code allows you to enter text (called a comment) into the code. Everything from the apostrophe to the end of the line will be ignored. Multiplication is represented by an asterisk (*). Division is represented by a forward slash (/).

Microsoft Visual Basic 2005 BASICS37 Summary (cont.) The Fix function removes the fractional portion of a number and performs an operation called truncation. Integer division is represented by a backward slash (\) and returns only the whole number portion of the division of integers. The modulus operator (Mod) returns the remainder of integer division.