CS 424

Final Exam Explained

Reasons for studying concepts of programming languages (5 Reasons)

Better Understanding, Increase Computational idea capacity, Ability to learn languages, Compare Two languages for better use in situation, significance of implementation

Readability

How easy a programming language is to read, ie syntax

Writability

Measure of ease to write solutions

Reliability

Degree to which programs perform without errors

Cost

Time for development, time, or resources used

Simplicity

How very easily understandable and basic a language is. Impacts writability and readability

Orthogonality

These symbols mean exactly what they mean and there is a lack of extra conditions. Real life example is changing the TV channel which doesn’t change the volume or anything else

Non-Orthogonality

Allows for another thing to happen when writing the code. Real life example is something like a helicopter changing direction as speed increases

Von Neumann

The architecture that is most commonly used

Imperative

data oriented programming language. Think the language C.

Object Oriented Programming

Object focused languages like C++

Interpreted

Doesn’t turn into binary to execute or just not compiled. Example is Javascript

Hybrid

High level to intermediate language which combines compiled and interpreted. Example is Java or C#

Compiled

Language will go through a compiler before executing. Example is C++

Static

Compile time legaility checking

Dynamic

Run time legality checking

Compiled VS Interpreted VS Hybrid

Compiled - Faster to execute, slower to write
Interpreted - Slower to execute, Faster to write
Hybrid - Very average between the other two

Syntax

Form that dictates how a language is written

Semantics

Meanings of what has been written from the language

Lexemes

Characters

Tokens

Sets of characters

Lexical Analysis

Valid characters being used check

From Lexical Analysis to Tokens

Symbols that the language can understand

Tokens to Syntactic Analysis

Valid statements being written

From Syntactic analysis to Compute

Has to check for valid data to compute the syntax

BNF Stands for

Backus Naur Form and is the Natural notation for describing syntax

Parse Tree

Used based on the BNF grammar rules.
If given someyhing like assign, expression, term, fact, id. order would as written. ID is usually created using two “ marks

Precedence

PEMDAS in Math or a vertical movement

Associativity

Which to do based off of rules on the same horizontal level. Such as Multiply or Divide on the same level

Ambiguity

More than 1 parse tree can be created from the expression

Attribute

Left Side

Predicate

Right side of grammar

Names

String of characters used to identify an entity in a program

Reserved Word

A special word that cannot be used as a name

Address of Variable

memory location

Type of variable

classification

Binding of Variable

value association

Scope of variable

range of statements where variable is visible

Lifetime of variable

time bound to a memory location

Name of a variable

in code identifier

Data type

types that have predefined logical operations

Pointer

refers to an address within memory

References

refers to an object or value within memory

Gabrage Collection

frees up no longer used memory

Dangling pointers

pointers that point to a memory location that is not valid

Side Effects

function alters memory locations outside of the scope

Widening

Upcast like int → Float

Narrowing

Downcast like double → float

Coercion

process of converting one type of data type to another

Imperative Programs

2 forms of control statements
Selecting among alternatives = if else
Repeating Selected Statements = for & while loops

One Way

Selects between 2 actions based on a single condition. If statement

Two way statement

If- Else

Multi-way statement

Switch, n-many if, case, elif

Examples

Iterative Statement - For Loop

Condition Controlled Loops - While

Count Controlled Loops = For Loop

Iteration based on data structure

iterator similar to a python for loop

Communicating Sequential Processes

Interactions between concurrent processes. IE multithreading

Guarded Commands

Basis for communicating sequential processes for a non-deterministic program

Fundamentals of Subprograms

Only load as they come into memory

One single entry

Control retunred to caller at termination

Subprogram

Self contained part of code that can be called anywhere within the program

Call

explicit request for execution

Active

subprogram is in execution

Header

type and parameter profile

Body

executable logic

Formal Parameters

Defined in header

Actual Parameters

values passing in

Positional Parameters

Refers the actual to the formal parameters

Keyword Paraemeters

name of formal used to map to actual parameters. Think of an alias

Default Parameters

default values passed if nothing is sent in

Design Issues for Subprograms

1) Can they be overloaded?

2) What parameter passing methods are used?

3) Static or dynamic local variables?

Activation Record

organization of variables in addition to implementation of lifetime and scope of the variables in a table like set up

Run Time Stack

All stack frames at the current postion

Environment Pointer

Holds beginning of current activation recordD

Dynamic Link

link to location where called

Static Chain

start of each activation record

Static Depth

Integer that hold the value of each scope level

Nesting Depth

Difference of current scope depth and the depth of the variable access

Offset

Beginning of Activation Record to beginning of storage point

Deep Access

references to non local variables through dynamic links

Shallow Access

alternative way of implementing dynamic scope

Abstraction

Combining of logical operations

Process Abstractions

Hiding details of thread execution

Abstract Data Type

Data type’s behavior is from the user

Encapsulation

building data and methods into a single unit

Information Hiding

keeping information from the users

Required Features of OOP Languages and Definitions

Objects = Procedures and Data

instantiation = Creating an object from a class

Inheritance = making new classes by changing existing ones

Polymorphism = use of one symbol to represent many types

Single Inheritance

derived class rom a single base class

Multiple Inheritance

class derives from multiple parent classes

Generalization

subclass into a superclass

Specialization

Creates more specific classes from higher

Parent/Child

Class relationship where child inherits from parent class

Pure Object Oriented Language

Needs:
Small Talk
Everything as an object
Has encapsulation

Exception Handling and Event Driven similarities

Involved reading to specific occurrences within a system

Triggered by something happening

Decoupling Mechanisms

Design Issues for Exception Handling

Identify and categorize exceptions

Checked or unchecked exceptions

Granularity of exceptions

Creating without harming code readability

Functional Programming Languages

LISP, Haskell

Pure Functions to build and edit software

Math Functions

all functions are seen as deterministic math functions

Fundamentals of Functional Programming Languages

uses pure functions

recursions

cant modify variables

Basics of primitives

built in functions that operate on numbers, symbols, and lists

Basics of lists,numbers, and symbols

All fundamental data types

Doman and Range

X-Axis

Y-Axis

Referential Transparency

replaces properties without changing program’s behavior