different data types used in programming VB .pptx
- 2. The Name: Text. Birthdate: Date. Gender: Boolean value. Family members: numeric value
- 6. Each data type has: 1. A storage space in the memory: such as (Integer) when used It occupies (4 bytes). 2- A range of values: minimum and maximum range of values type Ex: (Byte) starts with "0" and ends with "255".
- 7. Constants and Variables Variables Constantans Defenition Are reserved Places in the computer 's memory that have Names and Data types that store values that can be changed during the execution of program Are reserved Places in the computer 's memory that have Names and Data types that store values that can not be changed during the execution of program Declaratio n Dim Dim Variable name As data Type Const Const constant name As Data Type = Value Ex Dim UserName As String Const Pi As Single =22/7
- 8. Rules for naming the Constants and variables: : 1. names must begin with a letter or underscore (_). 2. names Should not contain symbols or special characters (e.g.: ?,*,^, -, +,.) 3. Variable names consist of letters, numbers, and underscores (_). 4. Do not use reserved words (Visual Basic.NET Language Keywords) such as (single, Dim, As). 5. It is preferable that the Variable name reflects its content.
- 9. 1- Text valves are written between double quotes (" ") Const Cinema As string = "Royal" 2- (# #)are used while writing date or time. Const Birthdate As Date= #1/7/2011# Assignment statement:
- 10. Examples of values of assignment ststment 1) Abstract Value : Ex: Area =5 Text = "Egypt" 2) (Value from Variable ): Area = N1 3) (Value from Property): Name = TextBox1.Text 4) ( Value from expression): Area = Num1 +3 5) ( value from function) :Name= Sum(A,B) 6) (Value from Constant) : Area =3.14*R^2
- 11. Assignment Statement for Variables Dim Number As Integer Number = 500 Dim Number As Integer =500 1st Case :(we can write the assignment statement after declaration line) 2nd Case : (we can write the assignment statement during declaration in the same line) Const Pi AS Single =22/7 Assignment Statement for Constants has One case:- must be during declaration only