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 etc. 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
In order 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(return 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
Dim firstName As String
Dim secondName As String
Dim yourName As String
Private Sub Command1_Click()
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 user’s 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 above, three variables are declared as integer and two variables are declared as variant. Variant means the variable can hold any numeric data type. The program computes the total and average of the three numbers that are entered into three text boxes. In the coming Lessons, we will see how to write more complex VB programs using mathematical operators and equations