1. Numbers

2. Numbers Arithmetic Operations Display numbers in VB.NET Variables
Built_in Functions
Three types of errors
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3. Arithmetic Operations
Numbers are called numeric literals
Five arithmetic operations in VB.NET
+ addition
- subtraction
* multiplication * 2
/ division / 2
^ exponentiation ^ 2
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4. Precedence of Arithmetic operation
Level of precedence:
() Inner to outer,left to right
^ Left to right in expression
* / Left to right in expression
+ - Left to right in expression
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5. Scientific Notation
Scientific notation represents a number by using power of 10 to stand for zeros
In VB.Net
b • 10 r is written as bEr
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6. Scientific Notation 10 –20 10 ^ - 20 1E-20
r is two digit number preceded by plus sign if r is positive and by a minus sign if r is negative
10 – ^ E-20
1.2 • * 10 ^ E+13
VB.NET’s choice of whether to display a number in a scientific or standard form depends on the magnitude of the number
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7. Display numbers
One way to show numbers on screen is to display them in a list box.
lstNumbers.Items.Add(n)
- Display number n as the last item in the list box
lstNumbers.Items.Clear()
- Erase all the items in the list box
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8. Demonstration
List a set of numbers in a list box.
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9. Variables
A variable is a name that is used to refer to an item of data. The value assigned to the variable may change.
Up to 16,838 characters long
Begin with a letter or an underscore
Consist of only letters,digits and underscores
A Variable name is written in lowercase letters except for the first letters of additional words, such as costOfIT201.
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10. Data Type Type Stores Range Of Values Boolean Logical Values
True or False
Double
Float-Point Numbers
+/- 5E-324 to 1.8E308
Integer
Integers
-32,768 to 32767
Long
+/- 2 billion
Single
Floating Point Numbers
+/- 1E-45 to 3E38
String
Text Information
Fixed Length: 1 to 65,400
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11. Const constantName As dataType = value
Variable Declaration
Declaration:
Dim varName As dataType
Variable name
Data type
Const constantName As dataType = value
Variable that can’t change
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12. Variable Declaration
Dim declares a variable named varName to be of type dataType
Dim causes computer to set aside a location in memory with the same name varName
Dim also put the number zero in that memory location if varName is a numberic variable
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13. Multiple Declarations
multiple-declaration statements :
Dim a, b As Double
Dim a As Double, b As Integer
Dim c As Double = 2, b As Integer = 5
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14. Variable Initialization
Numeric variables are automatically initialized to 0:
Dim varName As Double
To specify a nonzero initial value
Dim varName As Double = 50
declares a variable named varName to be of type Double. Actually, the Dim statement
causes the computer to set aside a location in memory with the name varName. Since
varName is a numeric variable, the Dim statement also places the number zero in that
memory location. (We say that zero is the initial value or default value of the variable.)
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15. Assignment statement Assignment:(n is a literal) varName = n
varName = expression
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16. Rules for assigning variables
Assign Integer, Long data type to a variable to store whole numbers
Assign Single, Double to a variable to store decimal fraction
Assign String to a variable to store a list of characters
Assign Boolean data type to a variable whose value will be True or false
Assign Date data type to a variable to store date and time information
Assign Object data type to a variable to store reference to an object
Choosing the data type in each group depending on the size o
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17. Increment variable value
To add 1 to the numeric variable var
var = var + 1
Or as a shortcut
var +=1
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18. Built-in Functions
Functions associates with one or more values and returns a value(output)
Math.sqrt(n):
Returns the square root of n. Math.Sqrt(9) is 3
Int(n):
Returns greatest integer less than or equal to n
Int(9.7) is 3
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19. Built-in Functions Math.Round(2.5) is 2 Math.Round(n, r):
number n rounded to r decimal places
Math.Round(2.317,1) is 2.3
Math.Round(2.7) is 3
When n is halfway between two successive
whole number, then it rounds to the nearest
even number
Math.Round(2.5) is 2
Math.Round(3.5) is 4
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20. Three Types of Errors Syntax error – grammatical errors Run-time error
misspellings, omissions,incorrect
punctuation
Run-time error
occurs when program is running
Logic error
program doesn’t perform as it is intended
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