Bahasa-bahasa Pemrograman Sumber: Chapter 10. System Analysis & Programming: S/W Development, Programming, & Languages, p.497 Williams, B.K, Stacy C. Sawyer (2007). Using Information Technology: A Practical Introduction to Computers & Communications. Seventh Edition, McGraw-Hill, New York. ISBN-13: 978-0-07-110768-6

Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : menjelaskan apa itu pemrograman dan langkah-langkah dalam pemrograman (C2)

Programming: A Five-Step Procedure Outline Materi Programming: A Five-Step Procedure 5 Generations of Programming Languages Programming Languages Used Today Object-Oriented & Visual Programming Markup & Scripting Languages

Programming: A Five-Step Procedure A program is a list of instructions that the computer must follow to process data into information The five steps are Clarify/define the problem Clarify the program objectives & users Clarify outputs Clarify inputs Clarify processing tasks Study the feasibility of the program Document the analysis Design the program Code the program Test the program

Programming: A Five-Step Procedure Step 2: Design the program Create an algorithm or set of steps to solve the problem Traditional structured programming approach Determine program logic using top-down approach & modules Design details using pseudocode or flow charts Alternative object-oriented approach Use “Use Case” approach to determine program objects, object inheritance, and actions or functions each object can perform Identify major program components and organize related functions and associated data into object classes This is the approach used by object-oriented languages such as Java, C#, Lisp, Visual Basic, and C++ For more information on object-oriented programming, visit http://oopweb.com/ or http://java.sun.com/docs/books/tutorial/java/concepts/

Programming: A Five-Step Procedure A hierarchy chart

Programming: A Five-Step Procedure START DO WHILE (SO LONG AS) THERE ARE RECORDS Read a customer billing account record IF today’s date is greater than 30 days from date of last customer payment Calculate total amount due Calculate 5% interest on amount due Add interest to total amount due to calculate Grand total Print on invoice overdue amount ELSE ENDIF Print out invoice END DO END Panel 10.13 Pseudocode

Programming: A Five-Step Procedure ● PANEL 10.14 Example of a program flowchart and explanation of flowchart symbols This example represents a flowchart for a payroll program.

Programming: A Five-Step Procedure Iteration and sequence control structures

Programming: A Five-Step Procedure Step 3: Code the program Translate the logic requirements into a programming language Programming language is a set of rules that tells the computer what operations to do Each programming language has a syntax, or set of grammatical rules to follow to write valid expressions Syntax rules must be followed or there will be syntax errors Computers don’t understand what you want, only what you type in

Programming: A Five-Step Procedure Step 4: Test the program Desk checking is done by the programmer who checks for syntax errors and logic errors Debugging is the process of detecting, locating, and removing all errors in a computer program Beta testing is the process of testing the program using real data One phase of testing uses correct data Once the program works, the next phase of testing uses invalid data and untrained users to root out hidden errors

Programming: A Five-Step Procedure Step 5: Document & Maintain the program Documentation is written descriptions of what a program is and how to fix it There are several types of documentation that should be written User documentation – for the people who will use your program Operator documentation – for the people who run the large computers the program runs on – so they know what to do if the program or computer malfunctions Programmer documentation – for the next programmer who must modify and maintain what you have written Maintain the program Fix any errors that are noticed once the program is in production Update the program to reflect new requirements

Object-Oriented & Visual Programming In Object oriented Programming (OOP) data and processing instructions are combined into an object that can be reused Object Self-contained module consisting of reusable code Message The instruction received by the object indicating it is time to perform an action Method The processing instructions within the object to perform the specified action

Object-Oriented & Visual Programming Black Box Objects are like a black box in that the actions and the objects are specified, but the methods used are internal to the object This means the programmer that uses an object does not need to know how the program inside the object does what it does For example, Microsoft Excel is like an object Most of us use Excel without understanding what the programmers at Microsoft did to make Excel work If we had to know that, it would take a lot longer to learn how to use Excel! Programmers who use objects can write programs a lot faster, because objects save so much work

Object-Oriented & Visual Programming 3 basic concepts of OOP Encapsulation One object contains (encapsulates) both Data Relevant processing instructions Inheritance One object can be used as the foundation for other objects Objects can be arranged in hierarchies – classes and subclasses Objects can inherit actions and attributes from each other Polymorphism Allows a single definition to be used with different data types and different functions Means a message produces different results depending on the object it is sent to

Object-Oriented & Visual Programming Example of Inheritance Hierarchy with Specialization The “Door” class Actions performed by a door Subclasses of doors inherit from the door class, but also have their own unique actions and attributes Notice we only list the actions & attributes when they differ from those of class

Object-Oriented & Visual Programming Visual Basic is an example of visual programming Using a mouse, the programmer drags and drops objects on screen The objects are arranged to make up the graphical user interface for the program being written By double-clicking on those objects, the programmer can get into a coding window and write the programs to control the actions and behaviors of those objects This makes it fast and easy to build prototype user interfaces and get end-user approval before doing a lot of programming If you have Visual Basic installed on your school’s computers, this would be a great time to try it out.

Markup & Scripting Languages A markup language is a kind of coding or “tags” inserted into text that embeds details about the structure and appearance of the text. Open up a text editor such as Notepad or Wordpad, and enter the following text: Then save the file on your desktop. Name it sample.htm Now open your internet browser and view it by clicking “file open” and navigating to your desktop <body bgcolor = "yellow"> <h2> <p>My name is </h2> <b><i><font color=“red”>your name</font></i></b></p> And I <b><h1>love</h1></b> this class!!! </body>

Markup & Scripting Languages So how did this Turn into this? By HTML tags <body bgcolor = "yellow"> <h2> <p>My name is </h2> <b><i><font color=“red”>your name</font></i></b></p> And I <b><h1>love</h1></b> this class!!! </body> My name is your name And I love this class!!! The <body bgcolor = “”> tag defines the page color The <h2> tag means a heading of size 2 The <h1> tag means a heading of size 1 The <i> tag means to italicize the text The <b> tag means to bold the text The <p> tag means to start a new paragraph And the / inside a tag means to end that format There are a LOT of other HTML tags

Markup & Scripting Languages HTML Hypertext markup language Used to create web pages Also lets you insert a hypertext link in a web page VRML Virtual Reality Modeling for Markup Language is used to create three-dimensional web pages including interactive animation Requires special VRML browser to view those pages

Markup & Scripting Languages XML eXtensible Markup Language is a metalanguage written in SGML that allows one to facilitate easy document interchange on the internet XML lets you create your own tags XML statements define data content JavaScript Not the same language as Java An object-oriented scripting language that adds interactive functions to web pages

Markup & Scripting Languages ActiveX Developed by Microsoft as an alternative to Java for creating interactivity on web pages A set of controls or components that enable programs or content of almost any type to be embedded in a web page Often used by crackers to propagate viruses and/or trojans Before you allow an ActiveX component to download from your browser to your PC, make sure you trust that website!

Markup & Scripting Languages Perl A general-purpose programming language developed for text manipulation. Developed in 1987 by Larry Wall Now used for web development, network programming, system administration, GUI development, other tasks Widely used for web server programs to perform automatic tasks such as updating user accounts and newsgroup postings