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

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

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

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

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

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

[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

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

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

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

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

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

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

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

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

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