Programming & Computers

Transcription

1 Programming & Computers CS Kaminski CS1110 focus 1. Problem solving Understand problem & requirements (I P O) Design modular program Design algorithms Code solution Test & debug 2. Programming PP (Procedural Programming) OOP (Object-Oriented Programming) 3. Language: Java (basics) 4. IDE: NetBeans (basics minor focus) 2 a computer Laptop, desktop [CS1110 focus] Mainframe, supercomputer Tablet, smart phone, Tivo, Xbox, Server: print server, file server, DB server, web server, 2 parts Hardware (HW) [read chap 1 in book] 1. CPU 2. Memory (RAM, ) 3. Storage: disk, thumb drive, 4. I/O devices 5. Connectivity: network, wifi, bluetooth, ethernet, Software (SW) [CS1110 focus] application programs (vs. Systems programs) makes computer smart controls HW hides most HW from user 3 4 HW -bits, bytes, words 1 byte = 8 bits a bit is either ON (1) or OFF (0) 1 word = 4 bytes (32-bit system) = 8 bytes (64-bit system) word contain: Machine language INSTRUCTION or DATA: 1 char ( A ) stored in 1 byte (or 2 if Unicode) 1 integer ( ) stored in 4 bytes etc. 5 SW (= programs) system SW OS, utilities, device drivers, compilers, network application SW general-purpose DBMS, MS Office, browser application-specific payroll, WMU registration, most ios / Android apps 6 1

2 Program recipe detailed step-by-step set of INSTRUCTIONS tells computer EXACTLY what to do controls HW processes data an algorithm a solution to a problem, implemented in a programming language Types of Programmers Application programmer Systems Database Network Web... AI Games programmer 7 8 Software Engineer Programmer Systems Analyst - Developer - Designer SW Engineer Plan, design, code, test, document GUI (Graphical User Interface) Program modules (classes, methods) main Code (= write program) Customize pre-written package Algorithm set of well-defined steps to do a specific task steps done sequentially (unless ) algorithm translated to machine language algorithm written in pseudocode or flowchart or... developer implements algorithm in a high-level language (like Java) compiler (or ) produces machine language (all 0 s and 1 s) 9 IPO (IPSO) model Input Processing Output & Storing HUMAN see/hear IPO model [think & remember] speak/write HW mouse/kb [CPU & RAM & disk] screen, SW data [process & store] data (user/file/db) (user/file/db) ^^^^^^^^^^^^^ the PROGRAM

3 IPO -SW Data windows application PROGRAM user input [process & store] screen display mouse clicks DB data in a form a program METHOD input parameters [procedure] return value [& local variables] [& class s instance variables] text, numbers graphics, sound, images, movies,... mouse clicks (single/double, left/right), mouse hovers, smartphone shakes... web page, text message, Types of applications Batch processing Typically: file in, file/printer out Interactive simple text I/O with user (Console App) GUI (Windows App) Web App - Java can do all of these - CS1110 mainly Console Applications Windows vs. Console App Input Event-driven Windows app PUSHed into program by user Console app PULLed into program by program Controller user program (main) Interface windows/gui/ visual/web/... console (text) Mode interactive batch or simple text I/O Types of Programs Event-driven program Modular program Visual program Structured program Procedural program Object-oriented program (OOP) - overlap - Java can do all of these - CS1110: Modular/Structured/ Procedural/OOP 17 Event-driven programming IPO: event [handler module in program] effects Events: left-mouse-click on button, mouse hovers over X, user hits F5 key, sensor detects iphone shake, change made to DB,... Program: set of modules to handle ANY event that could happen 18 3

4 Modular programming Program = a collection of small modules A module is: (in Procedural Programming) an IPO procedure or function (in Object Oriented Programming) a Class (object) a IPO method (~ a procedure) in a class Programming = write modules Top-down or bottom-up Visual Programming Visual C#, Visual Basic, Java with library of classes 1) Construct GUI from pre-existing components Text box, radio button, slider bar, dropdown list,... 2) Adjust properties of these objects 3) Add procedural code (a module) specifying: WHAT to do for each EVENT that might happen to this object (Much code is auto-generated for an object) Structured Programming Program/methods made from STACKING or NESTING: 1) Sequence Structures do action1, do action2, do action3,... 2) Selection (decision condition) Structures if conditionx is true then do action1,... else do action2,... 3) Repetition (loop) Structures while conditiony is true then { do action1, do action2,... } 21 Procedural Programming (PP) older languages mainly PP a procedure = named set of statements which do a specific task program is a set of procedures procedure (function) operates on program s data Data passed in to procedure Procedure returns resulting data 22 Object-Oriented Programming (OOP) OOP focus: create objects (vs. procedures) Object = combination of BOTH 1. Data = the attributes of the object 2. Procedures that manipulate that data - methods = behaviors of the object - services that users of the object might need OOP Encapsulation - combine data & behaviors Data hiding = object X s data not visible to other parts of program Only object X s methods can directly manipulate object X s data Other objects can only access/manipulate object X s attributes VIA object X s public service methods 4

5 Programming Determine: WHAT needs to be done HOW to do it (algorithm) = problem-solving solution 1) Solve the right problem AND 2) Solve the problem right A Good Program Produces correct output Follows client/designer s specs o functionality o output Runs fast Is compact (space) Clear & easy to change Example Problems iphone/android app List Song titles in alpha order on ipod Calculate final grade in CS1110 Pay off a car loan of size: amount at interest rate %: rate over? Years: numyears Google Maps find shortest route Kalamazoo San Francisco Steps in programming 1. Requirements specification (what) o input, processing, output 2. Program design (how) o algorithm, modules, GUI 3. Coding (development) [in Java] 4. Testing & debugging o compile errors & logic errors & runtime errors o validate output results 5. Documentation (external) 6. Maintenance Algorithm ( P of IPO) EXAMPLE: find sum of 1 st 100 integers User s view: BLACK-box Programmer s view: WHITE ( clear )-box (write & test actual code) Program s processing could: Look it up in a table / file / DB Crowdsource micro-task on internet Calculate using Algorithm A: Calculate using Algorithm B: (100 * (100+1)) / 2 Construct program from pre-existing classes/methods in library only need to know method s interface classes/methods written by programmer

6 Basic Program Operations 1) Actual Work arithmetic comparison ( =, <, >, and, or, not) 2) Move/store data Assignment Memory Memory I/O (Read) keyboard /mouse/touchscreen s touch/file/ Memory I/O (Write) Memory screen/printer/file/ 3) Control the flow (what instruction executes next) default: do next line maybe do this line (if, switch) do this multiple times (loop) goto & return (call) 4) Packaging methods (procedures) classes Pr.Language Generations 1 st ) Machine Languages (ML) s programmers wrote in ML Machine-dependent - each CPU has its own ML (Mac vs. PC) 2 nd ) Assembly Languages Add 210(8,13) Machine-dependent 3 rd ) High Level Languages (HLL) Java, C, C#, C++, Python, Ruby, PHP, Visual BASIC, Not processor-dependent but usually needs machine-specific compiler average = (ex1 + ex2 + ex3) / 3; main programming paradigms Procedural (PP) o C, COBOL, Fortran, Basic,... o any OOP language can do PP Object-oriented (OOP) o Java, C#, C++, Visual Basic,... o Newer versions of COBOL, th ) Application-specific Languages e.g., SQL for DBS (describe WHAT not HOW) Select name, phone from student where major = CS and state = MI ; 5 th ) Natural Languages (English,...) If patient is age 65 or older and is disoriented and has pain in his/her left arm then patient could have had a heart attack 35 6