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2. Objectives Declare and initialize a one-dimensional array
Store data in a one-dimensional array
Display the contents of a one-dimensional array
Code a loop using the For Each…Next statement
Access an element in a one-dimensional array
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3. Objectives (continued)
Search a one-dimensional array
Compute the average of a one-dimensional array’s contents
Find the highest entry in a one-dimensional array
Update the contents of a one-dimensional array
Sort a one-dimensional array
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4. Objectives (continued)
Enter code in the form’s Load event procedure
Create and manipulate parallel one- dimensional arrays
Create and initialize a two-dimensional array
Store data in a two-dimensional array
Search a two-dimensional array
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5. Using Arrays Simple variable Array Also called scalar variable
Is unrelated to any other variable in memory
Array
A group of variables that have the same name and data type and are related in some way
You can picture an array as a group of small adjacent boxes inside the computer’s memory
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6. One-Dimensional Arrays
Visualize as a column of variables
Each variable is identified by a unique number
Unique number is called “subscript”
Subscript is placed inside parentheses immediately following array name
Example strStates(1) – read “strStates sub one”
Individual variables referred to as “elements”
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7. One-Dimensional Arrays (continued)
Declare using keywords Dim or Private
highestSubscript argument in declaration used to specify the number of elements in the array
number of array elements is 1 more than the value in highestSubscript argument
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8. One-Dimensional Arrays (continued)
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9. HOW TO…
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10. Storing Data in a One-Dimensional Array
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11. Manipulating One-Dimensional Arrays
Sample procedures will demonstrate how to perform tasks using a one-dimensional array
Display contents of an array
Access an array element using its subscript
Search the array
Calculate the average of the data stored in a numeric array
Find the highest value stored in an array
Update the array elements
Sort the array elements
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12. Displaying the Contents of a One-Dimensional Array
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13. Displaying the Contents of a One-Dimensional Array (continued)
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14. The For Each…Next Statement
Use to code a loop containing instructions to be processed for each element in a group
Syntax template shown in next slide contains words “element” and “group”
“element”
Declare a variable of the same data type as the elements of the array and place this variable in the “element” position of the template
“group”
The variable name of the array
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15. HOW TO…
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16. Using the Subscript to Access an Element in a One-Dimensional Array
Display salary amount corresponding to code entered by user
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17. Searching a One-Dimensional Array
Determine number of salespeople selling above a certain amount
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18. Calculating the Average Amount Stored in a One-Dimensional Numeric Array
Calculate and display average test score earned by students on final exam
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19. Determining the Highest Value Stored in a One-Dimensional Array
Display highest amount earned in a week
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20. Updating the Values Stored in a One-Dimensional Array
Procedure allows manager to increase price of each item and display item’s new price
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21. Sorting the Data Stored in a One-Dimensional Array
Array.Sort(arrayName) method
Sorts the elements of a one-dimensional array in “ascending order”
First element contains smallest value
Last element contains largest value
To sort in descending order
First sort in ascending order
Then use Array.Reverse(arrayname) method to reverse the position of the elements in the array
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22. Sorting the Data Stored in a One-Dimensional Array (continued)
btnSortAscending_Click procedure sorts intNumbers array into ascending order
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23. Sorting the Data Stored in a One-Dimensional Array (continued)
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24. Sorting the Data Stored in a One-Dimensional Array (continued)
Method sorts array in descending order and displays the results
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25. Sorting the Data Stored in a One-Dimensional Array (continued)
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26. Using a Module-Level One-Dimensional Array
Application displays names contained in a sequential access file, giving user choice of ascending or descending order of display
First, declare array variable in the Form’s general declarations section
Then, fill array from data in file using code in the form’s Load event procedure
Load event occurs before the first time a form is displayed
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27. Using a Module-Level One-Dimensional Array (continued)
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28. Using a Module-Level One-Dimensional Array (continued)
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29. Parallel One-Dimensional Arrays
Two or more one-dimensional arrays whose elements are related by their position (subscript)
Called parallel because element at subscript 0 in first array corresponds to element at subscript 0 in another array
Example:
strID(0) corresponds to intPrice(0) and
strID(1) corresponds to intPrice(1),
and so on…
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30. Parallel One-Dimensional Arrays (continued)
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31. Parallel One-Dimensional Arrays (continued)
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32. Parallel One-Dimensional Arrays (continued)
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33. Two-Dimensional Arrays
Resemble a table in that variables are store in rows and columns
Each element is identified by a unique combination of two subscripts
The first subscript indicates the element’s row
The second subscript indicates the column
Each subscript begins with 0
The element in the first row and column has a subscript of (0,0)
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34. Two-Dimensional Arrays (continued)
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35. HOW TO…
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36. Storing Data in a Two-Dimensional Array
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37. Searching a Two-Dimensional Array
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38. Programming Example – Perrytown Gift Shop Application
Application is to assist in employee weekly payroll process
Calculates and displays the federal withholding tax (FWT)
Gets and displays taxable wages
Gets and displays marital status
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39. TOE Chart
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40. User Interface
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41. Objects, Properties, and Settings
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42. Objects, Properties, and Settings (continued)
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43. Tab Order
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44. Pseudocode btnExit Click event procedure close application
btnCalc Click event procedure
Include the following in a Try/Catch block:
remove any dollar signs and spaces from the txtTaxable control
assign the taxable wages store in txtTaxable to a variable
assign the marital status entered in txtStatus to a variable
if marital status is not either M or S
display an appropriate message
else
if marital status is M
use the Married tax table, stored in an array
use the singles tax table, stored in an array
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45. Pseudocode (continued)
end if
Repeat while there are still rows in the tax table to search and taxable wages have not been found
if taxable wages are less than or equal to value stored in the first column of the current row in tax table
use information stored in 2nd, 3rd, and 4th columns in tax
table to calculate the federal withholding tax
indicate that the taxable wages were found by assigning the
value True to blnFound variable
else
add 1 to the contents of the intRow variable to continue the search
row in the tax table
Display the federal withholding tax in the lblFwt control
Use general Catch statement to handle and display any errors
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46. Code
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47. Code (continued)
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48. Summary
Programmers use arrays to temporarily store related data in computer’s internal memory
All variables in an array have the same name and data type
Each element in a one-dimensional array is identified by a unique subscript
Appears in parentheses after array’s name
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49. Summary (continued)
Each element in a two-dimensional array is identified by a unique combination of two subscripts:
Row subscript
Column subscript
Subscripts appear in parentheses after the array’s name
You list the row subscript first, followed by a comma and the column subscript
The first subscript in a one-dimensional array is 0 (zero)
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50. Summary (continued)
First row subscript in a two-dimensional array is 0 (zero) likewise, the first column subscript also is 0 (zero)
When declaring a one-dimensional array, provide either highest subscript or initial values
When declaring a two-dimensional array, you provide either the highest row and column subscripts or the initial values
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51. Summary (continued)
The number of elements in a one-dimensional array is one more than its highest subscript
The number of rows in a two-dimensional array is one more than its highest row subscript likewise, the number of columns is one more than its highest column subscript
You usually use an assignment statement to store data in an array
You refer to an element in a one-dimensional array using the array’s name followed by the element’s subscript
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52. Summary (continued)
You refer to an element in a two-dimensional array using the array’s name followed by the element’s row and column subscripts, which are separated by a comma
You can use the For Each…Next statement to code a loop whose instructions you want processed for each element in an array
You can use the Length property to determine the number of elements in the array
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53. Summary (continued)
You use the Array.Sort method to sort the elements in a one-dimensional array
You use the Array.Reverse method to reverse the order of the elements in an array
The elements in parallel arrays are related by their subscript (or position) in each array
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