CS Midterm 2023

program

set of instructions that a computer follows to perform a task

software

what programs are referred to as

programmer/software developer

a person with the skills necessary to design, creat, and test computer programs

Hardware

the physical components of a computer

Central Processing Unit

part of the computer that runs programs or software

microprocessors

tiny chips that are used as CPUs today

control unit

one of two parts of the CPU, coordinates all of the computer’s operations

logic unit (ALU)

one of two parts of CPU, designed to perform mathematical operations

Fetch

the CPU’s control unit fetches the next instruction in order from the main memory

Decode

The instruction is encoded as a number, the control unit decodes the instructions

Execute

the signal is routed to a component and the signal causes the component to perform an operation

Random Access Memory (RAM)

main memory, where the computer stores a program while it is running, usually volatile

Volatile Memory

only used for temporary storage while a program is running

bytes

what a computer’s memory is divided into

Bit

each byte is divided into 8 bits, standing for binary digit

Secondary Storage

type of memory that can hold data for long periods of time, where programs are usually stored

disk drive, solid-state drives

common secondary storage devices

memory cards, USB

external storage devices

CD, DVD

optical devices that are popular for data storage

Input

any data the computer receives from the outside world

input device

device that collects the information and sends it to the computer, keyboards, mouse, touch screen, scanner

Output

any information the computer sends to the outside world

Output Device

formats and presents output, computer screens, printers, speakers

Operating system

the most fundamental set of programs on a computer

Utility programs

performs a specialized task that enhances the computer’s operation data

Software development tools

the tools programmers use to creat, modify, and test software

application software

programs that make a computer useful for everyday tasks

Algorithm

set of well-defined steps for performing a task or solving a problem

machine language

sequence of binary numbers which the CPU interprets as commands

Programming languages

use words instead of numbers to program

low-level language

close to the level of the computer, resembles numeric language

high-level language

easiest language for people to understand

portability

can be written on one computer and run on many other types of systems

text editor

similar to a word processing program, used to write code

source code

statements written by the programmer

source file

file the code is saved in

preprocessor

reads the source code and looks for #

directives

cause the preprocessor to amend or process the source code in some way

compiler

steps through the preprocessed source code translating the source code instructions into the appropriate machine language instruction

syntax errors

illegal uses of key words, operators, punctuation, and other language elements

object code

translated machine language instructions

object file

where the object code is stored

run-time library

collection of code in C++ that contains hardware-specific code

linker

combines the object file with the necessary library routines

executable file

contains the machine language instructions and is ready to run on the computer

executable code

machine language instructions

Key Words

words that have special meaning and can only be used for their intended purpose

Programmer-Defined identifiers

words defined by the programmer

operators

perform operations on one or more operand

punctuation

mark the beginning or end of a statement or separate items in a list

Syntax

rules that must be followed when constructing a program

line

a single line as it appears in the body of a program

statement

complete instruction that causes the computer to perform some action

variable

a named storage location in the computer’s memory for holding a piece of data

variable definition

the type of variable along with its name

three-step process

gathering input, performing some process, producing output

top-down design

dividing your problems into small problems and solving them one by one

flowchart

a diagram that shows the logical flor of a program

Pseudocode

cross between human language and a programming language

Logic errors

mistakes that cause a program to produce incorrect results

desk-checking

the programmer starts reading the program and steps through each statement by hand

function

group of one or more programming statements that has a name

stream object

works with streams of data

stream-insertion operator

the item is inserted into the output stream

escape sequence

a backslash followed by a control character, used to control the way output is displayed

assignment statement

assigns a value to a variable

assignment operator

=

literal

a piece of data written directly into a program’s code

identifier

a programmer-defined name that represents some element of a program

Legal Identifiers

the first character must be A-Z, after that any letter, numbers or underscore can be used

short int

2 bytes

unsigned short int

2 bytes, positive only

int

4 bytes

unsigned int

4 bytes, positive only

long int

4 bytes

unsigned long int

4 bytes, positive only

long long int

8 bytes

unsigned long long int

8 bytes, positive only

float

4 bytes, single precision

double

8 bytes, double precision

long double

8 bytes, long double precision

null character or null terminator

marks the end of the string

boolean expressions

have a true or false value

true

1

false

0

scope

the part of the program a variable can be used

Unary operators

only require a single operand (-5)

negation operator

the minus sign when used in front of a number

binary operators

work with two operands

Ternary operators

require three operands

prompt

lets the user know that an input is expected

stream extraction operator

extras characters from the input stream so they can be used in the program

input/keyboard buffer

an area in memory where characters from the keyboard are temporarily placed

arguments

information being sent to a function

relational expression

expressions comparing two values

decision structure

allow statements to execute only under certain circumstances

conditionally executred

performed only when a certain condition exists

nested if

allows you to test more than one condition to determine which block of code should be executed

loop

control structure that causes a statement to repeat

pretest loop

tests its condition before each iteration