Computer Terms Good to Know

System A group of independent but interrelated elements comprising a unified whole

Computer System Hardware Software Data People

Hardware Mechanical, magnetic, electronic, and electrical devices comprising a computer system: CPU, disk drives, keyboard, or screen

Software Programs used to direct the operation of a computer, as well as documentation giving instructions on how to use them Operating System Software Applications Software

Data Facts, statistics, or items of information A collection of facts from which conclusions may be drawn Examples: Data: 123456789 Information: 123-45-6789

People Human beings, as distinguished from animals or other beings Required in order to interpret the data received from a computer system

Operating System Software Software required to support the production or execution of application programs but which is not specific to any particular application Examples: Windows, UNIX, Linux, MacOS, VM

Application Software A program used for a particular application Examples include: Document Processing (Word) Spreadsheets (Excel) Database (Access) Communications, Browsers, & e-Mail (Firefox) Education & Learning (West Point Bridge) Entertainment & Gaming (Halo Reach)

Things a Computer System Can Do Input Process Storage Output

Input Noun: Data or signals entered into a system for processing or transmission Verb: To enter data into a system

Process Noun: A running software program or other computing operation Verb: To perform operations on data

Storage Noun: Device into which data can be entered, in which they can be held, and from which they can be retrieved at a later time Verb: (Store) To hold information for use at a later date

Output Noun: Information in a form suitable for transmission from internal to external units of a computer, or to an outside medium. Verb: To transfer data from internal storage to an external medium, as paper or microfilm

Variables “A named space in main memory that holds a value that can be changed” Can hold information Temporary space in main memory Available while program or function runs Released when program or function ends

Variable Naming Rules Must start with a letter May contain letters & numbers May NOT contain spaces or special characters Except may contain underscore or dash Should make sense Might be case sensitive

Computer Program Statements Sequential: Taken in a sequence Decision or Selection: The process of making a choice Iteration or Loop: A repetition of a statement or statements in a program

Sequential Taken in a sequence The next following the previous A program will execute (follow the instructions in) one line at a time When a line of instruction is complete, the program processes the next line in sequence

Decision or Selection The act or process of making a choice The computer will decide if a statement will be executed based on the outcome of some condition being true Syntax is usually “if (condition is true) { perform these statements }”

If Syntax if(condition) { execute statements when condition is true }

If Else Syntax if(condition) { execute statements when condition is true } else { execute statements when condition is false

If Else If Syntax if(condition1 is true) { execute statements when condition1 is true } else if(condition2 is true) { execute statements when condition2 is true

Switch Case Syntax Switch(variableName) { case value1: execute statements when variableName is value1; break; case value2: execute statements when variableName is value2; break; case value3: execute statements when variableName is value3; break; default: execute statements when no values match }

Iteration or Loop A repetition of a statement or statements in a program The computer will decide to execute one or more statements again based on the outcome of some condition being true Syntax is usually “while (condition is true) { perform these statements }”

Loop Definitions Sentinel - A symbol, mark, or other labeling device indicating the beginning or end of a unit of information Sentinel Value - In programming, a special value that is used to terminate a loop Sentinel Variable - The variable that contains the sentinel value

3 Parts to Every Loop Start - the condition of the sentinel variable at the start of the loop Test - test the sentinel value against some stopping value, the loop will repeat when the condition is true Change - change the value of the sentinel so that, at some time, the test will become false & the loop will not repeat

Different Loops For While Do While (Different languages may have differences)

For Loop Execute a code segment more than once Loops while some condition is true Use when you know how many times

For Loop Syntax for(sentinelVariableStartValue; sentinelVariableTestCondition; sentinelVariableChange) { statements when condition is true }

While Loop Execute a code segment more than once Loops while some condition is true Use when you don't know how many times to loop If the condition is false the first time this will NOT execute even once

While Loop Syntax initialize sentinelVariableValue while(test sentinelVariableValue) { statements when condition is true change sentinelVariableValue }

Do While Loop Execute a code segment more than once Loops while some condition is true Use when you don't know how many times to loop If the condition is false the first time this will execute at least once

Do While Loop Syntax initialize sentinelVariableValue do { code segments when condition is true change sentinelVariableValue } while(test sentinelVariableValue)