Visual Basic .NET BASICS

Lesson 4

Mathematical Operators

2

Objectives

Describe the purpose of operators and how calculations are performed in Visual Basic .NET.

Create label controls. Use the addition and assignment operators. Use text boxes to get data from the user and

use the Val function to extract a numeric value from a text box.

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Objectives (continued)

Split code statements among the lines in the code window.

Use the subtraction operator. Use unary minus. 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.

4

Performing Calculations in Visual Basic .NET

Like other programming languages, Visual Basic .NET allows you to use mathematical equations in your programs.

Operators are symbols that perform specific operations in Visual Basic .NET statements.

The symbols “*” and “/” are used to represent multiplication and division in Visual Basic .NET.

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Creating Label Controls

The Label control is used to place text in a form.

Sometimes a label is used to identify a text box or to add a title or message to a form.

Labels can also be used to provide output.

To provide output, you write code for the desired calculation.

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Using the Addition and Assignment Operators

The addition operator (+) and the assignment operator (=) perform just as you would expect.

The term hard-coded refers to information that is entered directly into the source code and cannot change while the program runs.

7

Using Text Boxes and the Val Function

Text boxes are the fields placed on dialog boxes and in other windows that allow the user to enter a value.

The Text property of a text box specifies what text will appear on the text box.

8

How Text Differs from Numeric Data

In a computer, text – which can include letters, symbols, and numbers – is treated differently than strictly numeric information.

Numbers in a text box must be converted to a true numeric value before they can be used in a calculation.

Understand that the characters entered in text boxes need to be converted from text to a numerical value before mathematical operations can be performed.

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Using the Val Function

The conversion necessary to convert the numeric text characters in a text box to numeric values is done by the Val function.

The Val function takes numbers that are in text format and returns a numeric value that can be used in calculations.

10

Splitting Code Statements among Lines

Visual Basic .NET provides a way to split a line of code among two or more lines.

Within a line of code, you can key the underscore, known as the line-continuation character.

The line-continuation character tells the compiler to skip the next line and treat the text there as if it were a part of the same line.

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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.

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Using Unary Minus

You can use the subtraction operator as unary minus to perform negation, which means making a positive value negative or making a negative value positive.

The addition operator can be used as a unary plus.

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Using Fix

Most programming languages include a function that drops the fractional part of a number.

This process is called truncation. In Visual Basic .NET, the Fix function

returns a truncated whole number.

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Performing Integer Division and Using the Modulus Operator

In computer programming, there are times when you want to work exclusively with whole numbers called integers.

For cases when you want to work strictly with integers, Visual Basic .NET provides two special operations: integer division and modulus.

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Performing Integer Division

Integer division returns only the whole number portion of the division of integers.

Integer division is performed using the backslash (\).

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Using the Modulus Operator

Modulus returns the remainder of integer division.

The modulus operator is (Mod).

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Summary

Visual Basic. NET allows you to use mathematical equations in your programs.

Operators are symbols that perform specific operations in Visual Basic. NET statements. The addition operator (+) adds values. The assignment operator (=) assigns the result of the expression on the right of the operator to the item to the left of the operator.

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Summary (continued)

The subtraction operator (–) subtracts the value to the right of the operator from the value to the left of the operator. The subtraction operator can be used to perform negation. When used in this way, the subtraction operator is called the unary minus.

Values keyed directly into Visual Basic. NET code are called hard-coded values or literals.

19

Summary (continued)

Text boxes are the fields placed on dialog boxes and in other windows that allow the user to enter a value.

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.

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Summary (continued)

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.

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.

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Summary (continued)

Multiplication is represented by an asterisk (*). Division is represented by a forward slash (/).

The Fix function removes the fractional portion of a number. The Fix function performs an operation called truncation.

Integer division is represented by a backward slash (\). Integer division returns only the whole number portion of the division of integers. The modulus operator (Mod) returns the remainder of integer division.