CHAPTER 1: PROGRAM DEVELOPMENT LIFE CYCLE. Prepared for: CSC 128 Fundamentals of Computer Problem Solving

Transcription

1 CHAPTER 1: PROGRAM DEVELOPMENT LIFE CYCLE Prepared for: CSC 128 Fundamentals of Computer Problem Solving

2 Najwa Abd Ghafar UiTM OBJECTIVES OF THIS CHAPTER In this chapter, you will learn about: The steps to do programming How to develop an algorithm How to write simple computer program in C++ Syntax and logic error

3 COMPUTER SYSTEM Najwa Abd Ghafar UiTM What is a Programming Language? Programming Language: Is used by programmers to write computer programs It is used to write instructions written by programmer in order to tell the computer what to do Most people refer programming language to high level language

4 Najwa Abd Ghafar UiTM HOW A C++ PROGRAM IS PROCESSED MyProgram.c pp Program is written in C++ MyProgram.o bj Program is translated into Machine Language MyProgram.e Program is xe combined with programs from library and is ready for execution SOURCE CODE (.cpp) OBJECT CODE (.obj) EXCECUTABL E FILE (.exe) Compiler Translates source program into Machine Language Linker Link the object program with other programs from the library

5 Najwa Abd Ghafar UiTM PROBLEM SOLVING PROCESS What is Programming? Programming: Is a process of PROBLEM SOLVING Before you can write your codes inside the computer, you NEED TO KNOW HOW TO SOLVE the problem first

6 Najwa Abd Ghafar UiTM PROBLEM SOLVING PROCESS To solve a problem, you should follow the steps below: 1. Analyze the Problem Start by outlining the problem Design an algorithm 2. Implement the Algorithm Use a programming language (C++) to prove that the algorithm works 3. Maintain the Program Modify the program wherever necessary

7 Najwa Abd Ghafar UiTM PROGRAM DEVELOPEMENT LIFE CYCLE Program Development Life Cycle (PDLC): Act as a guide for programmers when building a program Analysis Maintenance Design Testing Implementati on

8 Najwa Abd Ghafar UiTM PROGRAM DEVELOPMENT LIFE CYCLE 1. Problem Analysis: When analyzing a problem, you need to determine: 1. Input: What kind of data do you need from the user 2. Process: What do you need to do get your output 3. Output: What do you want to display to the user INPUT PROCESS OUTPUT

9 EXAMPLE Najwa Abd Ghafar UiTM Analyze the following problem: Find the summation of 2 numbers Use an IPO table for Problem Analysis Input Process Output 1 st number 2 nd number sum = 1 st number + 2 nd number The sum of 2 numbers is sum

10 QUICK EXERCISE Najwa Abd Ghafar UiTM Analyze the following problem: The program should print out your name and the phrase C++ is my favourite subject!

11 QUICK EXERCISE Najwa Abd Ghafar UiTM Analyze the following problem: Find the total of days within the month of June, July and December.

12 QUICK EXERCISE Najwa Abd Ghafar UiTM Analyze the following problem: Find the perimeter of a rectangle

13 Najwa Abd Ghafar UiTM PROGRAM DEVELOPMENT LIFE CYCLE 2. Algorithm Design: What is an ALGORITHM? Algorithm: Is a set of sequential instructions that are followed to solve a problem

14 Najwa Abd Ghafar UiTM PROGRAM DEVELOPMENT LIFE CYCLE Algorithm for finding the summation of 2 numbers (BEFORE refinement as pseudocode): 1. Read 2 numbers 2. The summation of 2 numbers is calculated by adding up the 1 st number and the 2 nd number 3. Display the summation of 2 numbers that was calculated Basically, algorithm is a STEP-BY-STEP instructions on how to solve a problem HOWEVER, when human language is used, the meaning of the sentence can be imprecise at times (what is written might be different than how it is read)

15 Najwa Abd Ghafar UiTM PROGRAM DEVELOPMENT LIFE CYCLE 2. Algorithm Design: Therefore in order to make an algorithm more precise, there are 2 ways an algorithm can be designed: 1. Pseudocode: In written form 2. Flowchart: In a graphical form These algorithm design is more precise because: Uses limited vocabulary Make use of variables

16 Najwa Abd Ghafar UiTM PROGRAM DEVELOPMENT LIFE CYCLE 2. Algorithm Design: Pseudocode: Is an algorithm in written form (text-based) by using a human language The flow of algorithm should be written in sequence with: A start An end TIP: The flow of your pseudocode can clearly be seen when you do numbering for each step

17 EXAMPLE Najwa Abd Ghafar UiTM Design a pseudocode for the following problem: Find the summation of 2 numbers 1. Start 2. Display Enter the 1st number 3. Read num1 4. Display Enter the 2nd number 5. Read num2 6. sum = num1+ num2 7. Display The sum of 2 numbers is and sum 8. End INPUT PROCESS OUTPU T

18 QUICK EXERCISE Najwa Abd Ghafar UiTM The following pseudocode algorithm has an error. The program is supposed to ask the user for the length and width of a rectangular room, and then display the room s area. The program must multiply the width by the length in order to determine the area. Find the error. 1. Begin 2. area = width x length 3. Read width 4. Read length 5. Display The area of the room is and area 6. End

19 QUICK EXERCISE Najwa Abd Ghafar UiTM Design a pseudocode for the following problem: The program should print out your name and the phrase C++ is my favourite subject!

20 QUICK EXERCISE Najwa Abd Ghafar UiTM Design a pseudocode for the following problem: The program should find the total of days within the month of June, July and December.

21 QUICK EXERCISE Najwa Abd Ghafar UiTM Design a pseudocode for the following problem: The program should find the perimeter of a rectangle

22 QUICK EXERCISE Najwa Abd Ghafar UiTM Design a pseudocode for the following problem: Determine whether a person is eligible to enter the theme park based on their age. Appropriate message should be given to that person: Age Less than 10 Between 10 and 49 Description Not eligible because you re too young Eligible to enter 50 or more Not eligible because it might be dangerous

23 Najwa Abd Ghafar UiTM PROGRAM DEVELOPMENT LIFE CYCLE 2. Algorithm Design: Flowchart: Is an algorithm in graphical form which is made up of symbols The flow of algorithm should be written in sequence with: A start An end This algorithm design allow us to see the actual flow of the program

24 Najwa Abd Ghafar UiTM PROGRAM DEVELOPMENT LIFE CYCLE Flowchart Symbols: Symbols Use of Symbols Start / End Input / Output Process Decision Connector Flow Line

25 EXAMPLE Najwa Abd Ghafar UiTM Design a flowchart for the following problem: Find the summation of 2 numbers Start A Read num1, num2 Display The sum of 2 numbers is, sum sum = num1 + num2 End A

26 QUICK EXERCISE Najwa Abd Ghafar UiTM Design a flowchart for the following problem: The program should ask for the user s age and display the following message This year you are years old.

27 QUICK EXERCISE Najwa Abd Ghafar UiTM Design a flowchart for the following problem: Find the average of 5 numbers.

28 QUICK EXERCISE Najwa Abd Ghafar UiTM Design a flowchart for the following problem: Determine whether a person is eligible to enter the theme park based on their age. Appropriate message should be given to that person: Age Less than 10 Between 10 and 49 Description Not eligible because you re too young Eligible to enter 50 or more Not eligible because it might be dangerous

29 QUICK EXERCISE Najwa Abd Ghafar UiTM Design a flowchart for the following problem: Find the largest of 3 numbers.

30 Najwa Abd Ghafar UiTM PROGRAM DEVELOPMENT LIFE CYCLE 3. Algorithm Implementation: Once the algorithm is designed and has been correctly verified, the algorithm can now be implemented But HOW? This is when you do your CODING inside the computer by FOLLOWING the algorithm that you have designed

31 EXAMPLE Najwa Abd Ghafar UiTM The following is a program that will find the summation of 2 numbers: #include <iostream> using namespace std; int main() { int num1, num2, sum } cout << "Enter the 1st number: "; cin >> num1; cout << "Enter the 2nd number: "; cin >> num2; sum = num1 + num2; cout << "The sum of 2 numbers is : "<< sum return 0; INPUT PROCE SS OUTPU T

32 Najwa Abd Ghafar UiTM PROGRAM DEVELOPMENT LIFE CYCLE Compiling: Once you have finished writing your codes, you can try and run your program But WHAT DO YOU NEED to run your program? COMPILER: Will ensures that your program follows the constructs of the language (a.k.a NO SYNTAX ERROR!!) When there are no syntax error, it will then translate the program into machine code

33 Najwa Abd Ghafar UiTM PROGRAM DEVELOPMENT LIFE CYCLE 4. Program Testing: Your program should be tested with all types of data and cases so that you can find and eliminate errors Errors is also known as bugs The process of removing bugs is called debugging

34 Najwa Abd Ghafar UiTM PROGRAM DEVELOPMENT LIFE CYCLE Possible Errors in a Program: 1. Syntax Error: Also known as compile-time error Occurs during compilation when you incorrectly write a command or some other part of the program 2. Logic Error: Occurs when a program runs, but unexpected results are produced Often produced by an incorrect algorithm. 3. Runtime Error: Also known as execution-time error Occurs during execution, which results in an error message and an abnormal end to program execution (program crash).

35 QUICK EXERCISE Najwa Abd Ghafar UiTM Answer the following questions: 1. What type of error occurs when you misuse a C++ language, similar to a grammatical error? 2. What type of error occurs when your code doesn t perform the task it s intended to perform? 3. What type of error occurs when there is a severe logic error that prevents your program form executing? 4. What type of error would be identified by the compiler?

36 Najwa Abd Ghafar UiTM PROGRAM DEVELOPMENT LIFE CYCLE 5. Program Maintenance: Involves you modifying or upgrading the existing program or system It is important to document your program so that you and other programmers can make changes or updates later There are 3 types of documentation: 1. Documentation in the Program: Comments can be used to explain certain codes 2. Documentation outside the Program: Diagrams, flowcharts or descriptions can be used to explain how the programming problem was solved 3. Documentation for the User: User documentation or user manual is used to explain the functions of the program