My Error= Thanks Chisolm

Blog Task: Mismatched data

The InvalidCastException occurs if the wrong data type is used, if there is a data mismatch

If you enter a number within the integer range the program executes as it should

The correct data type to store a string in is a string 

The correct data type to store a number in is an integer

You can store a number in a string variable as long as you declare it as a string and are not using it for any mathematical reasons 

Blog Task: Looping through the array

The upperbound of the array is 2

3 elements are contained within the array

I suggest as a starting value of 0 and an ending value of 2

The code in figure 4 produces an IndexOutOfRangeException because the loop is trying to access an index that is beyond the upperbound of the array, in this case the upperbound of the array is 2 and the loops ending condition is 3, the exception is thrown when the intLoopCounter reaches 3 because it should really be 2

The value that is displayed in the message box when the loop is in it’s second iteration is string 2

Blog Task: Warnings

Visual Studio IDE provides a warning with regards to using variables before they have been assigned a value, this warning is as follows: 

#use the "new" keyword to create an object instance 

#check to determine if the object is null before calling the method 

The warning pops up in a box and has a yellow box around the code that is incorrect, it also contains a green squiggly line under in this case ThisPlayer1.

Blog Task: Name that function

The name of the Visual Basic function we could use to ensure that only numeric data is assigned to the integer variable (therefore avoiding the program crash if non-numeric data is entered)?:isNumeric

We implement this method by using an If IsNumeric statement

Overflow exception (error) occurs when a value goes beyond its data type's storage capacity

The range/capacity of an integer is -2,147,483,648 through 2,147,483,647

 

Blog Task: Types of errors

The three types of errors or exceptions include: 

syntax errors, run-time errors, and logic errors

Let me explain them in more detail below:

Syntax errors:

#the most common type of errors

#As you write the code this is when they appear

#As you type the code into the editor VB checks the code and lets you know if and when a mistake has been made

#If you spell a word wrong or if you do not use a language element properly VB will let you know

# As soon as this error happens you can fix them in the coding environment

Run-time errors:

#After you compile and run your code this is when run time errors appear

# No syntax errors show and for this reason the code may appear to be right, however the code will not run

# eg: you write code to open a file, you do this the right way, corruption of the file may occur and for this reason the open function stops running because the application cannot carry out this function.

# Re-write this non working code to  fix this issue, then recompile and rerun the code

Logic errors:

#When the application is in use these errors occur

# In response to the users actions logic errors are unexpected and unwanted

# eg: The application may stop working all together or just stop working within parameters that are expected because of an outside influence or mistyped key

#These errors are difficult to fix, it is not always easy to source where they have come from

3/8/2010 Overiding

A Student Class

STUDENT

(private) #

#Name

#Number

#Fees

New (Name, Number, Fees)

Calculate Fees() : Integer

Children Class:

On Campus Student

-CampusID

New( CampusID)

Another Child Class:

Online Student

-CourseKey

New(CourseKey)

Another Child Class:

International Studen

-RegionalCode

New (RegionalCode)

CalculateFees()

STUDENT class implementation:

Public Overidable Function CalculateFees () As Integer

End Function

International Student Implementation:

Public Overides Function CalculateFees () As Integer

3/8/2010 Constructor and Method Overloading

Constructor overloading : Multiple constructors

The parameter lists must be unique, the same data type cannot be used more then once

New()

New(Name As String)

New(Name As String, Age As Date)

Method Overloading

A Simple Class :

Player

-HealthLevel: Integer

+ New()

+ SetHealthLevel(HealthLevel:Integer)

+SetHealthLevel(HealthLevel:Integer,Bonus:Boolean)

Code : 

Private _Health As Integer

Public Sub SetHealth(HealthLevel As Integer)

_HealthLevel = HealthLevel

End Sub

Public Sub SetHealth (HealthLevel As Integer, Bonus As Boolean) 

_HealthLevel = HealthLevel *2

End Sub

Loop Revision Task 2

Questions / Answer 

The upper Bound of the array is 2 

3 elements are contained in the array 

The starting index of the array is 0 

The starting value of the loop counter is 1 

The loop executes 3 times  

The concatenation operator joins two character strings end to end: it is the ampisand

Loop Revision Task 1

The loop counter is intLoopCounter

The loop executes 100 times

The final value of the NumberAccumulator variable is 100

2/8/2010 - Loops

For intx = 1 To intTotalNumberOfCells

intx = 1 is the starting condition

intTotalNumberOfCells is the ending condition