chapter 3 - visual basic schneider numeric variables used to store numbers value is assigned by a...

Chapter 3 - Visual Basic Schneider

Numeric Variables

• Used to store numbers • Value is assigned by a statement of the form:

numVar = expression

• The variable must be on the left and the expression on the right.


Assignment Statement:

• The statement var = expr assigns the value of the expression to the variable

• tax = 0.02 * (income - 500 * dependents)• sum = 2 + x + 4.6 + y


Valid Numeric Variable Names:timeElapsed taxRatespeedncelsius


Invalid Numeric Variable Names:• maximum/average• 1stChoice• square yard


Valid Assignment Statements

• count = count + 1• num = 5 • count = count + num /2


Invalid Assignment Statements• 10 = count• count + 1 = count


Visual Basic Print Statement• Print is a method used to display data on the

screen or printer.• Can be used to display values of variables or

expressions


Examples of Print Statements

Private Sub cmdCompute_Click() picResults.Print 3 + 2 picResults.Print 3 - 2 picResults.Print 3 * 2 picResults.Print 3 / 2 picResults.Print 3 ^ 2 picResults.Print 2 * (3 + 4)End Sub


Examples of Print Statements• picOutput.Print speed• picOutput.Print taxRate• picOutput.Print “Class average is”; total / 3


Examples of Print Statements x = 15 y = 5picOutput.Print (x + y) / 2, x / y

Output: 10 3


String Constants:

• A sequence of characters treated as a single item

• The characters in a string must be surrounded by double quotes (“ ”)


Valid String Constants

“A rose by any other name”“9W”“134.23”“She said, ‘stop , thief!’ ”


Invalid String Constants

‘Down by the Seashore’“134.24“She said, “Stop, thief!””


String Variables• A string variable stores a string.• The rules for naming string variables are

identical to those for naming numeric variables.

• When a string variable is first declared, its value is the empty string.


String Variable Example

Private Sub cmdShow_Click() picOutput.Cls phrase = "win or lose that counts." picOutput.Print "It's not whether you "; phrase picOutput.Print "It's whether I "; phraseEnd Sub


Concatenation• Two strings can be combined by using the

concatenation operation.• The concatenation operator is the ampersand

(&) sign.


Examples of Concatenation:• strVar1 = “Hello”

strVar2 = “World”picOutput.Print strVar1& strVar2

• txtBox.Text = “32” & Chr(176) & “ Fahrenheit”


Declaring Variable Types

• Use the Dim statement to declare the type of a variable.

• Examples: Dim number As Integer Dim flower As String

Dim interestRate As Single

chapter 3 - visual basic schneider numeric variables used to store numbers value is assigned by a...

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