1. Programming Lifecycle
Chapter 1 (Cont..)
Programming Lifecycle
CSC425 - Introduction To Computer Programming

2. OBJECTIVES
 Introduce the general step programmers go through to develop computer programs and software
 Explain the phases in the system development life cycle.
CSC425 - Introduction To Computer Programming

3. Programming Life CycleD o c
ume n t a I
Problem Analysis
Programs Modelling
Coding Programs
Testing and Debugging
Maintenance
CSC425 - Introduction To Computer Programming

4. Step 1 : Problem Analysis
 Defining the problem
 Identify :
1. Input (given data)
2. Output (the result)
3. Process
- relation between input and output
- using formula
Input
Process
Output
CSC425 - Introduction To Computer Programming

5. Example
Problem 1
Write a program that can input 3 integer number from user. Find the average for the number. Display all the numbers and the average
Problem analysis
Input : 3 numbers
Process : 1. total up 3 numbers
2. Divide the number by 3
Output : 3 numbers and the average
CSC425 - Introduction To Computer Programming

6. Step 2 : Programs Modeling
 Planning the solution to a problem
 Using algorithm, flowchart or pseudocode
[Refer Problem 1]
1. Set sum = 0, avg = 0
2. Read 3 integer number
3. Total up 3 integer number
sum = a+b+c
4. Find the average
avg = sum / 3
5. Display 3 integer number and average
algorithm
CSC425 - Introduction To Computer Programming

7. [Refer Problem 1] Pseudocode Flowchart start sum =0 , avg = 0 START
Read a, b, c
sum = a+b+c
avg = sum / 3
Display a,b,c
Display avg
End
START
INPUT a,b,c
sum = a+b+c
avg = sum / 3
PRINT a,b,c
PRINT avg
END
Pseudocode
Flowchart
CSC425 - Introduction To Computer Programming

8. Step 3 : Coding and programs source code
 Express solution in a programming language
 Translate the logic from the flowchart or pseudocode.
 There are many programming languages : BASIC, COBOL, Pascal, Fortran, C, C++, Java etc
 Each language has it’s own syntax (rules of language)
CSC425 - Introduction To Computer Programming

9. [Refer problem 1] Coding in C++ Language Output of the program
CSC425 - Introduction To Computer Programming

10. Step 4 : Testing and Debugging
 Trace error either syntax or logic error
Testing
 running the program with a set of data
Debugging
 Trace and fixed the error
CSC425 - Introduction To Computer Programming

11. Occur during program execution Detected by compiler
Run-time error
Occur during program execution
Detected by compiler
Occur because of logic error or memory leak
Syntax error
Error in the structure or spelling of a statement
Detected by the compiler during compilation of the program
Example:
Missing semicolon, quote
CSC425 - Introduction To Computer Programming

12. Produce undesired result/output Cannot be detected by compiler
Logic error
Unexpected/unintentional errors resulted from flaw in the program’s logic
Produce undesired result/output
Cannot be detected by compiler
Compare the result with manual process
CSC425 - Introduction To Computer Programming

13. Documentation 1. Description of the program
 An ongoing process
 Written detailed description of the program cycle and specific facts about the program
 Documentation materials include :
1. Description of the program
2. Logic tools : flowcharts, pseudocode
3. Data- record descriptions
4. Program listing
5. Testing results
6. Comments
CSC425 - Introduction To Computer Programming

14. Why programmers put comment?
To explain/describe the program/function/statement
To help other programmers understand the program/function/statement
2 types of comments
Line comment: single line comment
Block comment: multiple line comment
Syntax comment is differ to certain languages
CSC425 - Introduction To Computer Programming

15. Step 5 : Maintenance  Modification made to the finished program
 Software to meet current requirement
 Need to refer the previous documentation
CSC425 - Introduction To Computer Programming

16. A good program must have
Accuracy
Reliability
Efficiency
A good program must have
Maintainability
Readability
Usability
CSC425 - Introduction To Computer Programming