Programming Creating programs that run on your PC (BTW- groups of programs are called software applications)

Learning Objectives Understand the differences between structured programming, object-oriented programming (OOP), aspect-oriented programming (AOP), and adaptive software development. Identify and describe the activities involved in the program development life cycle (PDLC). Understand what constitutes good program design and list several tools that can be used by computer professionals when designing a program. Understanding Computers: Today and Tomorrow, 14th Edition 2

Learning Objectives Explain the three basic control structures and how they can be used to control program flow during execution. Discuss some of the activities involved with debugging a program and otherwise ensuring it is designed and written properly. List some tools that can be used to speed up or otherwise facilitate the program development process. Describe several programming languages in use today and explain their key features. Understanding Computers: Today and Tomorrow, 14th Edition

Breaking into Program development From SDLC, break into PDLC Analysis What should it do? Design How will it do it? Develop Creation Implement Get rid of the “bugs” Maintain Keeping it running

Programs & Programming Computer program – a sequence of instructions for a computer written to perform a specific task Programming: Process of designing, writing, testing, debugging & maintaining the source code of computer programs Programs need to be designed before they can be developed One thing to remember: Programs use computer memory Space to Run in Space to save pieces of information in for later use (variables)

Programming Languages Programming – writing a computer program Write from scratch in selected language– write reusable code Use Software Development Kit (SDK) Use Application Programming interface (API) Programming language A set of rules, words, symbols, and codes used to write computer programs Programming Tools Flowcharts, business documents, models Categories of programming languages Low-level languages High-Level languages 4GL languages Once written, prepare for execution (running) .exe or .dll Loads in memory Uses memory to save information (variables)

Programming Languages Low Level High Level Difficult to code in; machine dependent Machine language: 1’s and 0’s Assembly language Includes some names and other symbols to replace some of the 1s and 0s in machine language Closer to natural languages Machine independent – run on windows and Mac OS’s Easier to learn Many generations (4), as time passes and hardware gets better Translated to machine language FORTRAN - mathematical, scientific, and engineering applications BASIC family (BASIC, Visual Basic, VB.NET) – games to web services COBOL - business transaction processing C family (C, C++, C#, objective C) – mainframes, web services, iPhones Pascal – for midrange servers – taught STRUCTURE Java - web services, applets – most popular today Python – todays games

Languages (LOW LEVEL – HIGH LEVEL) Programmers write comments in code to explain complicated parts (ignored by computer) Each programming language has its own set of rules to follow Many programming languages to choose from – 3rd gen are quite similar

Fourth Generation Languages Closer to natural languages Easier to work with than high-level Much of the code written is reusable! Mostly used with: Databases Includes structured query language (SQL) DB2, SQL Server, Oracle, Access, Foxpro, Powerbuilder, Natural, FOCUS Apps Software development kits (SDK’s) Web Services Application Program Interfaces(API’s)

PROGRAMMING LANGUAGES

Programmers write out complicated logic visually – in diagrams called flowcharts START Variable to indicate how many numbers we have gotten Variable to save the first number Variable to save the second number RESERVE MEMORY GET A NUMBER SAVE THE NUMBER IN MEMORY TELL MEMORY VARIABLE WE HAVE A NUMBER YES NO Got 2 numbers? ADD THE NUMBERS IN MEMORY DISPLAY SUM Other symbols, like an ellipse or circle, mean other things STOP

Creates .EXE WRITE THE PROGRAM USING CHOSEN LANGUAGE TRANSLATE THE PROGRAM (LANGUAGE COMPILER) INTO MACHINES LANGUAGE Programs can have errors Compiler errors: Program doesn’t run Typically syntax errors: When the programmer has not followed the rules of the programming language Run time error: Error that occurs when the program is running Usually an operation that cannot be completed Logic errors: Program will run but produces incorrect results Creates .EXE EXECUTE (RUN) THE PROGRAM - PROGRAM LOADS IN MEMORY, and USES MEMORY TO SAVE INFO USERS CLICK ON ICON TO RUN “APP” Programs use computer memory -Need “run space” Save pieces of information for later use (variables)

Approaches to Design and Development Procedural Programming Steps to accomplish task are separated into small modules and execute in a certain order or when needed Object-oriented Programs consist of a collection of objects that contain data and methods to be used with that data and are used when needed Aspect oriented Separates functions so program components can be developed and modified individually from one another One program does all the database work, another program presents the web page, etc.. Adaptive Building the program in small steps of functionality Understanding Computers: Today and Tomorrow, 14th Edition