Lesson 6: Working with Variables


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6.1 Assigning Values to Variables

After declaring various variables using the Dim statements, we can assign values to those variables. The general format of an assignment is

Variable=Expression

The variable can be a declared variable or a control property value. The expression could be a mathematical expression, a number, a string, a Boolean value (true or false) and more. The following are some examples:

firstNumber=100
secondNumber=firstNumber-99
userName="John Lyan"
userpass.Text = password
Label1.Visible = True
Command1.Visible = false
Label4.Caption = textbox1.Text
ThirdNumber = Val(usernum1.Text)
total = firstNumber + secondNumber+ThirdNumber

 

6.2 Operators in Visual Basic

To compute inputs from users and to generate results, we need to use various mathematical operators. In Visual Basic, except for + and -, the symbols for the operators are different from normal mathematical operators, as shown in Table 6.1.

Table 6.1: Arithmetic Operators
Operator
Mathematical function
Example

^

Exponential

2^4=16

*

Multiplication

4*3=12,  

/

Division

12/4=3

Mod

Modulus (returns the remainder from an integer division)

15 Mod 4=3   

\

Integer Division(discards the decimal places)

19\4=4

+ or &

String concatenation

"Visual"&"Basic"="Visual Basic"

Example 6.1

Private Sub Command1_Click()

Dim firstName As String
Dim secondName As String
Dim yourName As String

firstName = Text1.Text
secondName = Text2.Text
yourName = secondName + "  " + firstName
Label1.Caption = yourName

End Sub

In this example, three variables are declared as string. For variables firstName and secondName will receive their data from the userís input into textbox1 and textbox2, and the variable yourName will be assigned the data by combining the first two variables.  Finally, yourName is displayed on Label1.

Example 6.2

Dim number1, number2, number3 as Integer

Dim total, average as variant

Private sub Form_Click

number1=val(Text1.Text)
number2=val(Text2.Text)
number3= val(Text3.Text)

Total=number1+number2+number3

Average=Total/5

Label1.Caption=Total

Label2.Caption=Average

End Sub

In the Example 6.2, three variables are declared as integer and two variables are declared as variant. Variant means the variable can hold any data type. The program computes the total and average of the three numbers that are entered into three text boxes.

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