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Computer Programming

Section A. Programming Basics. CHAPTER 11. Computer Programming. PARSONS/OJA. Page 546. Section A. Chapter 11. Programming Basics. What is a computer program?.

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Computer Programming

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  1. Section A Programming Basics CHAPTER 11 Computer Programming PARSONS/OJA Page 546

  2. Section A Chapter 11 Programming Basics What is a computer program? • A computer program is a set of detailed, step-by-step instructions that tell a computer how to solve a problem or carry out a task • The instructions that make up a computer program are sometimes referred to as code • Today, program code contains familiar English-like words • Programs can exist as a single module or multiple modules Page 548-549

  3. Section A Chapter 11 Programming Basics What is a computer program? Page 548

  4. Section A Chapter 11 Programming Basics How big is a typical computer program? • A small-sized program has fewer than 100,000 lines of code • A medium-sized program has between 100,000 and 1 million lines • A large program has more than 1 million lines of code • On average, one person can write, test, and document only 20 lines of code per day Page 549

  5. Section A Chapter 11 Programming Basics Who creates computer programs? • A computer programmer typically focuses on creating computer programs • Coding refers to entering the list of commands that become a computer program • The term computer programming encompasses a broad set of activities that include planning, coding, testing, and documenting computer programs Page 549

  6. Section A Chapter 11 Programming Basics How does software engineering differ from computer programming? • Software engineering refers to a program development process in which mathematical, engineering, and management techniques are applied to reduce the cost and complexity of a computer program while increasing its reliability and modifiability • A software engineer design, codes, tests, and documents software, but tends to focus on designing and testing activities Page 549

  7. Section A Chapter 11 Programming Basics What is a programming language? • A programming language is a set of keywords and grammar rules designed for creating instructions that can ultimately be processed, or executed, by the computer • Keywords • Parameters • Syntax Page 550

  8. Section A Chapter 11 Programming Basics How are programming languages categorized? • Low-level languages vs. high-level languages • Generation • Paradigm Page 550

  9. Section A Chapter 11 Programming Basics What is a low-level language? • A low-level language typically includes commands that are specific to a particular CPU or microprocessor family • Includes machine languages and assembly languages Page 550

  10. Section A Chapter 11 Programming Basics What is a high-level language? • A high-level language hides the underlying low-level assembly or machine language, and provides command words and grammar that are more like human languages • COBOL • BASIC • Java • C Page 550

  11. Section A Chapter 11 Programming Basics What is a high-level language? Page 551

  12. Section A Chapter 11 Programming Basics What was the first generation of computer languages? • Machine languages were the first languages available for programming computers • First-generation languages • A machine language provides a set of commands, represented as a series of 1s and 0s Page 551

  13. Section A Chapter 11 Programming Basics What is a second-generation language? • An assembly language allows programmers to use abbreviated command words, called op codes, rather than 1s and 0s • Classified as a low-level language • Assembly languages are most often used to write system software Page 551

  14. Section A Chapter 11 Programming Basics What is a third-generation language? • Third-generation languages use easy-to-remember command words to take the place of several lines of assembly language or endless strings of machine language • COBOL • Fortran • Pascal • C • BASIC Page 551-552

  15. Section A Chapter 11 Programming Basics What is a fourth-generation language? • Fourth-generation languages more closely resemble human languages • Eliminate many of the strict punctuation and grammar rules complicating third-generation languages • Typically used for database applications • SQL • RPG-I Page 552

  16. Section A Chapter 11 Programming Basics What is a fourth-generation language? Page 552

  17. Section A Chapter 11 Programming Basics Do any fifth-generation languages exist? • Some believe a fifth-generation language is a computer programming language based on a declarative programming paradigm • Other experts feel fifth-generation languages are those that allow programmers to use graphical or visual tools to construct programs Page 552

  18. Section A Chapter 11 Programming Basics What is a programming paradigm? • The phrase programming paradigm refers to a way of conceptualizing and structuring the tasks that a computer performs • Multiparadigm languages support more than one paradigm Page 553

  19. Section A Chapter 11 Programming Basics What is a problem statement? • A problem statement defines certain elements that must be manipulated to achieve a result or goal • Specifies any assumptions that define the scope of the problem • Clearly specifies the known information • Specifies when the problem has been solved Page 554

  20. Section A Chapter 11 Programming Basics Program Coding: How do I code a computer program? • It depends on the programming language you use, the programming tools that you selected, and then programming paradigm that best fits the problem you’re trying to solve Page 555

  21. Section A Chapter 11 Programming Basics What is a generic text editor? • A generic text editor is any word processor that can be used for basic text editing tasks, such as writing e-mail, creating documents, or coding computer programs Click to start Page 555-556

  22. Section A Chapter 11 Programming Basics What is a program editor? • A program editor is a type of text editor specially designed for entering code for computer programs Page 556

  23. Section A Chapter 11 Programming Basics What is a VDE? • A VDE (visual development environment) provides programmers with tools to build substantial sections of a program by pointing and clicking • Form Design Grid • Control • Properties • Event • Event-handling code Page 557

  24. Section A Chapter 11 Programming Basics What is a VDE? Click to start Page 557

  25. Section A Chapter 11 Programming Basics What is a VDE? Page 558

  26. Section A Chapter 11 Programming Basics Is a visual development environment better than an editor? • It depends on whether a visual development environment is available for a specific programming language • VDEs are not available for every programming language • Microsoft Visual Basic was one of the first programming languages to feature a visual development environment • Event-driven paradigm Page 558

  27. Section A Chapter 11 Programming Basics How does a programmer know if a program works? • A computer program must be tested to ensure that it works correctly • Testing consists of running the program and entering test data to see whether the program produces the correct results Page 559

  28. Section A Chapter 11 Programming Basics What can cause program errors? • A syntax error occurs when an instruction does not follow the syntax rules, or grammar, of the programming language • Omitting . misspelling a keyword • A runtime error occurs when the computer can’t execute an instruction • Divide by 0 • A logic error is an error in the logic or design of a program • Incorrect formula Page 559

  29. Section A Chapter 11 Programming Basics How do programmers find errors? • Proofreading lines of code • Programmers can also use a debugger, which allows programmers to step through a program and monitor the status of variables, input, and output Page 559

  30. Section A Chapter 11 Programming Basics Do computer programs contain any special documentation? • User manuals • Help files • Programmers also insert remarks, which indicate how the code in a program works, in case others must modify the program Page 560

  31. Section B Procedural Programming CHAPTER 11 Computer Programming PARSONS/OJA Page 562

  32. Section B Chapter 11 Procedural Programming Algorithms: What is an algorithm? • An algorithm is a set of steps for carrying out a task, which can be written down and implemented • Carefully following the steps of a correctly formulated algorithm guarantees that you can accomplish the task for which the algorithm was designed Page 562

  33. Section B Chapter 11 Procedural Programming How do I write an algorithm? • Typically written in a format that is not specific to a particular programming language • This approach allows the programmer to focus on correctly formulating the algorithm, without being distracted by the detailed syntax of a computer programming language Page 562

  34. Section B Chapter 11 Procedural Programming How do I figure out an algorithm? • Record the steps you take to solve the problem yourself • The algorithm should: • Specify how the computer gets initial information • Specify how to manipulate this information • Specify how the computer decides what to display as the solution Page 563-564

  35. Section B Chapter 11 Procedural Programming What’s the best way to express an algorithm? • Structured English – a subset of the English language with a limited selection of sentence structures that reflect processing activities • Pseudocode – a notation system for algorithms that has been described as “a mixture of English and your favorite programming language” • Flowcharts – a graphical representation of the way that a computer should progress from one instruction to the next when it performs a task Page 565

  36. Section B Chapter 11 Procedural Programming What’s the best way to express an algorithm? Click to start Page 566

  37. Section B Chapter 11 Procedural Programming How do I know if my algorithm is correct? • Before finalizing the algorithm, perform a walkthrough to verify that your algorithm works • Step through the problem using realistic test data Page 567

  38. Section B Chapter 11 Procedural Programming Procedural Languages and Applications: What are the most popular procedural languages? • COBOL • FORTH • APL • ALGOL • PL/1 • Pascal • C • Ada • BASIC Page 573

  39. Section B Chapter 11 Procedural Programming What kinds of problems are best suited to the procedural approach? • Problems that can be solved by following a step-by-step algorithm • Transaction processing • Characterized by the use of a single algorithm applied to many different sets of data Page 574

  40. Section B Chapter 11 Procedural Programming What are the advantages and disadvantages of the procedural paradigm? • This approach tends to produce programs that run quickly and use system resources efficiently • Does not fit gracefully with certain types of problems • Unstructured problems • Complex algorithms • Forces programmers to view problems as a series of steps Page 574

  41. Section C Object-Oriented Programming CHAPTER 11 Computer Programming PARSONS/OJA Page 575

  42. Section C Chapter 11 Object-Oriented Programming What is the basic focus of the object-oriented paradigm? • The object-oriented paradigm is based on the idea that the solution for a problem can be visualized in terms of objects that interact with each other • An object is a unit of data that represents an abstract or real-world entity, such as a person, place, or thing Page 575

  43. Section C Chapter 11 Object-Oriented Programming What’s the difference between an object and a class? • A class is a template for a group of objects with similar characteristics CLASS: Pizza Page 575

  44. Section C Chapter 11 Object-Oriented Programming How do I define the classes that I need to solve a problem? • A class attributes defines the characteristics of a set of objects • A public attribute is available for use by any routine in the program • A private attribute can be accessed only from the routine in which it is defined • UML diagrams help plan the classes for a program Page 576

  45. Section C Chapter 11 Object-Oriented Programming How do I define the classes that I need to solve a problem? Page 576

  46. Section C Chapter 11 Object-Oriented Programming How do I code a class when writing a program? class Pizza { public string pizzaShape; public double pizzaPrice; public double pizzaSize; } Page 577

  47. Section C Chapter 11 Object-Oriented Programming Inheritance: How flexible are classes for defining different types of objects? • The object-oriented paradigm endows classes with quite a bit of flexibility • An OO feature called “inheritance” provides flexibility to deal with objects’ unique characteristics Page 577

  48. Section C Chapter 11 Object-Oriented Programming What is inheritance? • Inheritance refers to passing certain characteristics from one class to other classes • The process of producing new classes with inherited attributes creates a superclass and subclasses Page 577

  49. Section C Chapter 11 Object-Oriented Programming How do I code a subclass? • Java uses the “extends” command to link a subclass to a superclass class RectanglePizza extends Pizza { double pizzaLength; double pizzaWidth; } Page 578

  50. Section C Chapter 11 Object-Oriented Programming Methods and Messages: How does an OO program use objects? • Programs use objects to manipulate them with methods • A method is a segment of code that defines an action • Collect input • Perform calculations • Make comparisons • Execute decisions • Produce output Page 578

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