1. An Introduction to Programming with C++ Fifth Edition
Chapter 2
Beginning the Problem-Solving Process

2. Objectives
Explain the problem-solving process used to create a computer program
Analyze a problem
Complete an IPO chart
Plan an algorithm using pseudocode and flowcharts
Desk-check an algorithm
An Introduction to Programming with C++, Fifth Edition

3. Concept Lesson Problem Solving Solving Everyday Problems
Creating Computer Solutions to Problems
Analyzing the Problem
Planning the Algorithm
Desk-Checking the Algorithm
The Gas Mileage Problem
Summary
An Introduction to Programming with C++, Fifth Edition

4. Problem Solving In this lesson, you will:
Explore the thought process followed when solving problems
Learn how to use a similar process to create a computer solution to a problem
Called a computer program
An Introduction to Programming with C++, Fifth Edition

5. Solving Everyday Problems
First step in solving a problem: analyze it
E.g., problem of being hungry
Next, you plan, review, implement, evaluate, and modify (if necessary) the solution
E.g., if you are still hungry
An Introduction to Programming with C++, Fifth Edition

6. Solving Everyday Problems (continued)
An Introduction to Programming with C++, Fifth Edition

7. Solving Everyday Problems (continued)
An Introduction to Programming with C++, Fifth Edition

8. Creating Computer Solutions to Problems
Analysis tools: IPO charts, pseudocode, flowcharts
To desk-check or hand-trace, use pencil, paper, and sample data to walk through algorithm
A coded algorithm is called a program
An Introduction to Programming with C++, Fifth Edition

9. Creating Computer Solutions to Problems (continued)
An Introduction to Programming with C++, Fifth Edition

10. Analyzing the Problem Analyze a problem to:
Determine the goal of solving it
Output
Determine the items needed to achieve that goal
Input
Always search first for the output
An Introduction to Programming with C++, Fifth Edition

11. Analyzing the Problem (continued)
An Introduction to Programming with C++, Fifth Edition

12. IPO Charts
Use an IPO chart to organize and summarize the results of a problem analysis
IPO: Input, Processing, and Output
An Introduction to Programming with C++, Fifth Edition

13. IPO Charts (continued)
An Introduction to Programming with C++, Fifth Edition

14. IPO Charts (continued)
An Introduction to Programming with C++, Fifth Edition

15. Analyzing the Problem (continued)
First, reduce the amount of information you need to consider in your analysis:
An Introduction to Programming with C++, Fifth Edition

16. Analyzing the Problem (continued)
Worse than having too much information is not having enough information to solve problem:
An Introduction to Programming with C++, Fifth Edition

17. Analyzing the Problem (continued)
Distinguish between information that is missing and information that is implied:
An Introduction to Programming with C++, Fifth Edition

18. Planning the Algorithm
Algorithm: set of instructions that will transform the problem’s input into its output
Record it in the Processing column of the IPO chart
Processing item: intermediate value used by algorithm when processing input into output
Pseudocode is a tool programmers use to help them plan an algorithm
Short English statements
An Introduction to Programming with C++, Fifth Edition

19. Planning the Algorithm (continued)
An Introduction to Programming with C++, Fifth Edition

20. Planning the Algorithm (continued)
Flowcharts are also used to plan an algorithm
Use standardized symbols
Symbols connected with flowlines
Oval: start/stop symbol
Rectangle: process symbol
Represents tasks such as calculations
Parallelogram: input/output symbol
Represents I/O tasks
An Introduction to Programming with C++, Fifth Edition

21. Planning the Algorithm (continued)
An Introduction to Programming with C++, Fifth Edition

22. Planning the Algorithm (continued)
A problem can have more than one solution:
An Introduction to Programming with C++, Fifth Edition

23. Hints for Writing Algorithms
This problem specification is almost identical to the one shown earlier in Figure 2-4
An Introduction to Programming with C++, Fifth Edition

24. Hints for Writing Algorithms (continued)
You may use a portion of a previous solution to solve current problem
An Introduction to Programming with C++, Fifth Edition

25. Desk-Checking the Algorithm
An Introduction to Programming with C++, Fifth Edition

26. Desk-Checking the Algorithm (continued)
An Introduction to Programming with C++, Fifth Edition

27. Desk-Checking the Algorithm (continued)
Valid data is data that the programmer is expecting the user to enter
Invalid data is data that he or she is not expecting the user to enter
You should test an algorithm with invalid data
Users may make mistakes when entering data
An Introduction to Programming with C++, Fifth Edition

28. The Gas Mileage Problem
An Introduction to Programming with C++, Fifth Edition

29. The Gas Mileage Problem (continued)
After planning the algorithm, you desk-check it:
An Introduction to Programming with C++, Fifth Edition

30. Summary
Problem-solving typically involves analyzing the problem, and then planning, reviewing, implementing, evaluating, and modifying (if necessary) the solution
Programmers use tools (IPO charts, pseudocode, flowcharts) to help them analyze problems and develop algorithms
During analysis, you determine the output and input
During planning, you write the steps that will transform the input into the output
An Introduction to Programming with C++, Fifth Edition

31. Summary (continued)
After the analysis and planning, you desk-check the algorithm
Follow each of the steps in algorithm by hand
Coding refers to translating the algorithm into a language that the computer can understand
Before writing an algorithm, consider whether you have already solved a similar problem
An Introduction to Programming with C++, Fifth Edition

32. Application Lesson: Using the First Steps in the Problem-Solving Process
Lab 2.1: Stop and Analyze
Lab 2.2:
Create a program that the salesclerks can use to calculate and display the required number of rolls
Lab 2.3:
The program must now display the number of single and double rolls of wallpaper
Lab 2.4: Desk-Check Lab
Lab 2.5: Debugging Lab
An Introduction to Programming with C++, Fifth Edition