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Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 2
Objectives
• Understand the concept of an array
• Be able to declare arrays of various sizes
• Be able to populate and access the elements in an array
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 3
Objectives (cont.)
• Understand how to manipulate and process an array
• Consider multiple problems that benefit from an array solution
• Understand the Bubble Sort algorithm
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 4
4-1 Arrays
• An array is a variable that holds a collection of related data values.
• Each of the values in an array is called an element.
• Each element in the array is identified by an integer value called its index, which indicates the position of the element in the array.
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 5
4-1 Arrays (cont.)
• Most modern programming languages implement zero-based arrays, meaning that array index values begin with 0.
• The array length is the number of elements in the array.
• The upper bound of an array is the index of the last element.
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 6
4-1 Arrays (cont.)
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 7
Creating an Array
• In Visual Logic you create, or declare, an array using the Make Array command
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 8
Accessing Individual Elements of an Array
• To access individual array elements, you specify the array name and follow it with an index expression enclosed in parentheses.
• If you attempt to reference an array with an index value greater than the upper bound of the array, the result will be an out-of-bounds error.
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 9
When to Use Arrays
• Arrays are useful…– when you are storing or processing large
amounts of related data– when information must be stored and
processed twice
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 10
4-2 Above Average Problem (Mutual Funds)
• The Problem– Jim is a financial analyst with many large
investment clients. Each year Jim identifies ten different mutual funds that he shares with his clients for investing. At the end of each year he keeps the funds that performed better than the ten-fund average and replaces the others with new funds.
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 11
Analysis and Design
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 12
Analysis and Design (cont.)
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 13
4-3 Largest Value Problem(Highest GPA)
• The Problem– The Alpha Beta Gamma fraternity is one of
many popular Greek organizations on campus. Every semester, ABΓ recognizes the graduating brother who has the highest GPA. The number of graduates changes from semester to semester.
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 14
Analysis and Design
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 15
Analysis and Design (cont.)
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 16
Analysis and Design (cont.)
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 17
4-4 Working with Index Values(Two-Week Totals)
• The Problem– Anthony owns a small business and plans to
install new inventory hardware and software during the upcoming year. The installation process will require two weeks. To minimize the disruption that will occur during the migration, Anthony wants to deploy the system during the two weeks that had the lowest consecutive two-week total gross sales during the previous year.
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 18
Analysis and Design
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 19
Analysis and Design (cont.)
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 20
4-5 Simulation (Die Roll)
• The Problem– A balanced die is equally likely to roll a 1, 2, 3,
4, 5, or 6. If a balanced die is rolled many times, the roll values should be evenly distributed. As the number of rolls increases, the distributions should become closer to one-sixth, or 16.67 percent. What are the percentages after forty rolls? What are the percentages after four hundred rolls?
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 21
Analysis and Design
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 22
Analysis and Design (cont.)
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 23
4-6 Parallel Arrays(Girl Scout Cookies)
• The Problem– Every spring you look forward to buying a box
of Caramel deLites Girl Scout cookies from your niece, Belinda. Her troop gives an award to the girl who sells the most boxes of cookies each year. They are looking to develop a software solution to assist in determining the annual award winner.
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 24
Analysis and Design
• Parallel arrays are two or more arrays whose elements are related by their position in the arrays.
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 25
Analysis and Design (cont.)
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 26
Analysis and Design (cont.)
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 27
Chapter Summary
• An array is a variable that holds a collection of related data values.
• Most modern programming languages implement zero-based arrays.
• To access individual array elements, you specify the array name and follow it with an index expression enclosed in parentheses.
Crews/Murphy – Programming Right from the Start with Visual Basic.NET 1/e – ©2004 Prentice Hall 28
Chapter Summary (cont.)
• Arrays contain a finite number of elements, each of which is referenced by a unique index.
• Parallel arrays are two or more arrays whose elements are related by their positions in the arrays.
• Bubble Sort is a simple sorting technique involving multiple passes through the array.