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1 Technology in Action Behind the Scenes: Software Programming Topics System development life cycle Life cycle of a program Problem statement Algorithms Moving from algorithm to code Moving from code to machine language testing programs Completing a program Selecting the right programming language Most popular programming languages 1 2 What Is a Program? What is Programming A list of instructions Prewritten or packaged Off the shelf Custom-written Application software System software A problem-solving procedure Systems analysis and design involves general problem solving Programming a computer involves specific problem solving 3 4 What is Programming? The Life Cycle of a Program Programming is a six-step procedure for producing a program - a list of instructions - for the computer Six-step procedure-partpart of Phase 4: Systems Development Programming is the process of translating a task into a series of commands a computer will use to perform that task Programming g involves: Identifying the parts of a task the computer can perform Describing tasks in a specific and complete manner Translating the tasks into a language that is understood by the computer s CPU 5 6 1

2 What is Programming? Programming is software development Six step procedure 1. Program specification 2. Program design plan 3. Program code 4. Program test 5. Program documentation 6. Program maintenance Step 1 Programming Specifications (Describing the Problem) The problem statement is: The starting point of programming A description of tasks the program is to accomplish How the program will execute the tasks Created through interaction between the programmer and the user The program statement includes error handling and a testing plan 7 8 Step 1 Programming Specifications (Definition or Analysis) Step 1 Program Specifications Objectives Desired Outputs Input Data Processing requirements Document Specifications 9 10 PROGRAM GOAL: INPUTS: OUTPUTS: PROCESS: ERROR HANDLING: Parking Garage Example To compute the total pay for a fixed number of hours worked at a parking garage. Number of Hours Worked... a positive number Total Pay Earned... a positive number The Total Pay Earned is computed as $7.32 per hour for the first eight hours worked each day. Any hours worked beyond the first eight are billed at $11.73 per hour. The input Number of Hours Worked must be a positive real number. If it is a negative number or other non-acceptable character, the program will force the user to re-enter the information. TESTING PLAN: INPUT OUTPUT NOTES 8 8*7.32 Testing positive input 3 3*7.32 Testing positive input Plan and create a solution Use structured programming techniques Top-down program design Pseudocode d Flowcharts Logic structures 12 8* *11.73 Testing overtime input 6 Error message/ask user to re-enter value Handling error

3 Plan processing steps through top-down program design called program modules logically related program statements Top-Down Design Problem is divided into a series of high-level tasks Detailed subtasks are created from high-level tasks Top-Down 16 Developing an Algorithm Algorithm development: A set of specific, sequential steps that describe what the computer program must do Complex algorithms include decision points: Binary (yes/no) Loop (repeating actions) Visual tools used to track algorithm and decision points: Yes Head off to cafe Go get gas Buy textbook Go to accounting lecture Wake Up Check wallet for $ Do I have > $80 Yes Yes No No Do I have my credit card? No Go to the ATM for cash Did I get $80 from the ATM? 17 Flowchart and Pseudocode Flowchart Pseudocode Bold terms show actions that are common in programming, such as reading data, making decisions, printing, and so on. Pseudocode outline and summary of program Describes reasoning and logic for determining desired outputs 1. Ask the user how many hours they worked today 2. If the number of hours worked < = 8, compute total pay without overtime otherwise, compute total pay with overtime pay 3. Print total pay Compute Time for Client A Set total regular hours and total overtime hours to zero. Get time In and Out for a job. Compute hours past 1700 as overtime. Underlined words are information items that appear repeatedly in the algorithm. Add regular hours and add regular hours to total regular hours. Add overtime hours to total overtime hours. If more for client, go back and compute hours for next job

4 Flowchart Symbols Program Flowcharts Detailed sequence of steps displayed graphically Flowchart symbols Processing Input/Output Decision Connector Terminal Sequence Logic Structure Logic Structures Sequence structure Selection structure Loop structure One program statement follows another in logical order Selection Logic Structure (IF-THEN-ELSE) ELSE) Used when a decision must be made to determin e which of two paths to follow Loop (Iteration) Logic Structures (DO UNTIL OR DO WHILE) There are no more jobs As long as there are more jobs Iterates or repeats the process as long as a certain condition remains true two variations

5 Program Flowchart for Computing Time Worked Step 3 Program Code Coding Writing program from logic created in program-design step The good program Reliable Well documented Understandable to other programmers Structured programs using logic structures is best programming method Step 3 Program Code Coding is translating an algorithm into a programming language 28 Step 3 Program Code Which language? Determined based on logic Choose language best suited for needs, computer and system Formatting languages HTML, DHTML, XML, WML Programming languages C, C++, C#, Java, JavaScript, Visual Basic, COBOL, FORTRAN 29 Step 3 Program Code Selecting the right language: Based on logic, needs, computer system Space available, speed required Organizational resources available Type of target application programming or formatting language Visual Basic C / C++ Java HTML JavaScript VBScript Flash / XML ASP / JSP Compilation Compilation is the process of converting code into machine language Compiler reads the source code and translates it into machine language g Interpreter translates source code into a line by line intermediate form and each line is executed before the next line is compiled After compilation, programmers have an executable program

6 FAQs What is a program? What is a software engineer? What is the purpose of pseudocode? What are the qualities of a good program? Discuss design tools Describe program testing Summary Questions What is the life cycle of a program? What role does a problem statement play in programming? How do programmers create algorithms? How do programmers move from algorithm to code? Summary Questions How does a programmer move from programming code to the 1s and 0s the CPU can understand? How is a program tested? What steps are involved in completing the program? How do programmers select the right programming language for a specific task? What is Programming? Programming is software development Six step procedure 1. Program specification 2. Program design plan 3. Program code 4. Program test 5. Program documentation 6. Program maintenance Step 4 Program Test Debugging Testing Eliminating errors Syntax errors violations in rules of programming language Logic errors incorrect calculation or missing programming procedure Testing process Debugging Process of testing and eliminating errors

7 Debugging Running a program to find errors is known as debugging Integrated Development Environment: Tool in compilers and interpreters helps find syntax errors Sample inputs are used to determine runtime (logic) errors Debugger: Tool that pauses a program so programmers can step through the program to locate runtime errors 40 Step 4 Program Test Program testing sequence or process Desk checking (proofreading) Manual testing (one step at a time) with sample data Attempt at translation (compiler or interpreter) Testing sample data on the computer (execution) Users test the program (internal testing) Beta version released: Testing by a select group of potential users (beta testing) Information collected about errors before final revision 41 Step 5 Program Documentation Written descriptions and procedures about a program Important for people who will use the program Users Operators Programmers Step 5 Program Documentation Not an after-thought thought at the end of the programming process Prepared throughout of all the programming steps Different procedures for each group users, operators and programmers Software updates (service packs): Problems found after commercial release Documentation created: User manuals User training Step 6 Program Maintenance 75 % of total lifetime programming cost To ensure an error-free operations Efficient and effective programs Activity Categories Maintenance programmers Operational errors Changing needs Summary of Programming Steps Step Primary Activity Specification Objectives, I/O, process requirements Design Structured techniques Code Test Document Select and write Syntax and logic errors Users, operators, programmers 44 Maintenance Fix errors, update 45 7

8 CASE Tools Computer-aided software engineering (CASE) CASE tools automate the development process Code Generation Assistance Automate development process Designing Coding Testing activities Object-Oriented Oriented Software Development Focuses less on procedures, more on relationship between objects Object-oriented programming (OOP) Objects are reusable, self-contained components known as modules Object contains both the data and the processing operations to complete task Object-Oriented Oriented Analysis Object-oriented analysis Classes (categories of inputs) are identified Classes are defined by information (data) and actions (methods or behaviors) Objects are defined by their class, data and behavior Interaction between classes is determined Existing classes can be used for other projects 49 Object Oriented Programming (OOP) Object-oriented software development changes the approach Object-oriented e ted software development eop e Less reliance on traditional step-by-step approach Emphasis on defining relationships between procedures or objects already created 50 FAQs What is the job of a maintenance programmer in Step 6? Why is job important? Describe CASE tools & object-oriented oriented software development What is object-oriented oriented programming? FAQs Discuss the six steps to create a program. Describe the differences between formatting and programming languages. Give examples of each. Explain the debugging process for a program. Why is program documentation important?