1. 8 Records
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2. Learning Objectives State: The difference between records and arrays.
How to set up a record structure and declare an array of records.
How to store and retrieve the contents of an array of records.
How to declare a variable that is available on other forms.
How to refer to a variable declared as above another form.
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3. A Record Can store many items of data regardless of data type.
An array:
Can only store data of one type.
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4. An array of Records Each column is a field. Each row is a record.
Account Number
Surname
Forename
Balance
45278
Smith
Sally
€10.00
1208
Jones
John
€20.00
3217
Cain
Shazad
€100.00
4310
White
Peter
€250.00
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5. Declaring an array of records
Declare a single record globally.
Structure AccountStructure
Dim AccountNumber As Integer
Dim Surname As String
Dim Forename As String
Dim Balance As Decimal
End Structure
Declare an array of this record.
Dim Accounts(4) As AccountStructure
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6. Processing Records Accounts(1).Forename = “Sally”
Accounts(3).Balance = 100
lblDisplay.Text = Accounts(1).AccountNumber
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7. Declaring an array of records
Declare a single record globally.
Structure …
Dim … As …
End Structure
Declare an array of this record.
Dim …(…) As …
Record Name
Field Names
&
Data Types
No. of records req.
Record Array Name
Record Name (used above)

8. Declaring an array of records
This is like declaring your own data type.
The data type is a 1x1 array of field names of various data types.
Then you declare a variable which is a 1D array of the 1x1 data type.
Which will result in a 2D array of records.
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9. …(Element).FieldName Processing records Array of Records Name
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10. 8 Student Test Marks Specification:
Allow the user to enter up to 10 students and their test marks into an array.
Allow the user to search for student and see his/her test mark.
Allow the user to see all students and their marks.
Allow the user to reset and enter a new set of students and their marks.

11. 8 Student Test Marks txtName txtMark butAdd lblMark txtSearchName
butDisplayAStudent
butDisplayAllStudents
butReset

12. Set up an record structure
Name
Mark
Globally:
'The following will set up a Student Record with the "Name" and "Mark" fields.
Structure StudentStructure
Dim Name As String
Dim Mark As Integer
End Structure

13. Set up an array of records for 10 students
Name
Mark
Globally:
'Set up the Students Array with space 10 students.
'It will be used to store each student's name and mark.
Dim Students(10) As StudentStructure

14. Global Variable – NumberOfStudents
Also globally:
'Will be used to hold the number of students currently in the StudentsArray.
Dim NumberOfStudents As Integer

15. butAdd
'Increment the Number Of Students to move to next element in the Students Array.
NumberOfStudents = NumberOfStudents + 1

16. butAdd
'Store the name entered into the Name field of the Students Array.
Students(NumberOfStudents).Name = txtName.Text
'Store the mark entered into the Mark field of the Students Array.
Students(NumberOfStudents).Mark = txtMark.Text

17. butAdd 'Clear the name and mark entered. txtName.Text = ""
txtMark.Text = ""
lblMark.Text = ""
'Clear the list box which may be displaying previously entered students.
lstDisplayStudentMarks.Items.Clear()
'Put the cursor back into the name text box ready for a new student.
txtName.Focus()

18. butDisplayAStudent 'Will be used to store the required student name.
Dim SearchName As String
'Will be used to represent each element of the array.
Dim Element As Integer

19. butDisplayAStudent 'Store the required student.
SearchName = txtSearchName.Text

20. butDisplayAStudent
'Loop through each element of the Students array and look for the student name entered.
For Element = 1 To 10
'Has the student name been found?
If Students(Element).Name = SearchName Then
'If so, show the student's mark.
lblMark.Text = Students(Element).Mark
Exit Sub
End If
Next Element
'If the loop is finished then the student was not found. So tell the user.
MsgBox("The name was not found!")

21. butDisplayAllStudents
'Clear the list box from last time.
lstDisplayStudentMarks.Items.Clear()

22. butDisplayAllStudents
'Will be used to represent each element of the array.
Dim Element As Integer

23. butDisplayAllStudents
'Loop through the Students array and add each student's name and mark (with a space between) to the list box.
For Element = 1 To 10
lstDisplayStudentMarks.Items.Add(Students(Element).Name & " " & Students(Element).Mark)
Next Element

24. butReset 'Set the number of students back to 0. NumberOfStudents = 0
'Clear all text boxes, labels and the list box ready for a fresh set of students.
txtName.Text = ""
txtMark.Text = ""
txtSearchName.Text = ""
lblMark.Text = ""
lstDisplayStudentMarks.Items.Clear()
'Finish by the placing the cursor in txtName ready for a new student name.
txtName.Focus()

25. butReset Now: What happens? What should happen? Why does this happen?
Enter 5 student names and marks.
Search for a student you have entered and check the correct mark is returned.
Search for a student you have not entered and check you get a “Not found” message.
Display all students and their marks and check you get back the same results as you entered.
Click the reset button.
Enter 2 new student names and marks.
Display all students and their marks.
What happens? What should happen?
Why does this happen?
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26. butReset 'Loop through the array and clear each name and mark.
Add the following code to the Reset button.
‘All programs assume that the start values are 0 and
‘arrays may contain values from previous
‘processing. If they do then programs will use this
‘data and give incorrect results.
'Loop through the array and clear each name and mark.
Dim Element As Integer
For Element = 1 To 10
Students(Element).Name = ""
Students(Element).Mark = 0
Next Element

27. 8 Student Test Marks
Run the program and test it.

28. Commenting on Records
In presentation 8 I will only ask for comments to Records.
Your comments MUST explain:
What is the record for?
And if it is important: How many elements and why this number?
And when it is being used:
What are you storing or retrieving?
When (after and before what) are you doing this and why does it have to be done there?
When in the procedure code or, if it is on its own, in which procedure (button, checkbox, textbox, etc…)?

29. Extension “Estate Agency Records” Program 1
An Estate Agency has a program which stores details of the last 10 queries made. These are held in an array which contains, for each query made, the following:
The name of the customer
The number of bedrooms requested
The date on which the query was made
Whether the customer asked for details of a property or not (As Boolean – Yes/No).
Write a program which allows:
10 queries to be stored.
When a name is entered elsewhere on the form (textbox and button) it displays all their query’s details.
A button to display all queries stored (in another separate list box).
A reset button.
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30. Extension “Health Club” Program 2
Store the following details of members of a health club in an array of records:
Name
Date of Birth (DOB)
Weight (kg)
Height (m)
Write a program which allows:
Member details (as above) to be stored.
When a name is entered elsewhere on the form (textbox and button) it displays all their query’s details.
A button to display all member details stored (in another separate list box).
A reset button.
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31. Plenary
What is the difference between records and arrays?
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32. A Record Can store many items of data regardless of data type.
An array:
Can only store data of one type.
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33. Plenary
How can we set up a record structure and declare an array of records?
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34. Declaring an array of records
Declare a single record globally.
Structure AccountStructure
Dim AccountNumber As Integer
Dim Surname As String
Dim Forename As String
Dim Balance As Decimal
End Structure
Declare an array of this record.
Dim Accounts(4) As AccountStructure
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35. Plenary
How do we store and retrieve the contents of an array of records?
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36. …(Element).FieldName Processing records Array of Records Name
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