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Some important factors from "Concepts of Programming Languages (global edition) 11ed. - Robert W. Sebesta"

:Chapter 11, 12

⬥(p.472) Abstraction is a weapon against the complexity of programming; its purpose is to simplify the programming process.

⬥process abstraction: function/subporgrams

=> problem: side effect(touches variables other than itself  --> coupling modules occur)

⬥data abstraction: object-oriented

⬥an abstract data type is an enclosure that includes only the data representation of one specific data type and the subprograms that provide the operations for that type.(p.473)  ==>encapsulation, abstraction hiding

⬥constructor(used to initialize the data members of newly created objects.) VS destructor(implicitly called when the lifetime of an instance of the class ends.)

⬥interface vs implementation

⬥There are three key features that Object-Oriented languages must provide:

: Abstract data type(ADT), inheritance, dynamic binding(polymorphism)

⬥inheritance ==> customizing(reuse with modification): 1.override 2.add new member

⬥productivity increase: 1.reuse 2.automation

⬥class variables: only exist in class = not created in an instance

(if used in an instance, it means it has used the variable from a class)

⬥class method: can call from a class without an instance

Some important factors from "Concepts of Programming Languages (global edition) 11ed. - Robert W. Sebesta"

:Chapter 6

⬥FORTRAN: array & COBOL: record

⬥primitive data types(4): integer, float, boolean, character

⬥string operations: assignment, catenation, substring reference, comparison, pattern matching.

⬥3 approaches to supporting the dynamic allocation and deallocation for dynamic length strings

-linked list

-store strings as arrays of pointers to individual characters allocated in the heap

-store complete strings in adjacent storage

⬥2 types of structures(array, record) & tuple type/associative arrays

⬥purpose of pointers: indirect addressing, dynamic storage(dynamic variables in heap)

⬥garbage(p.302): an allocated heap-dynamic variable that is no longer accessible to the user program

⬥memory leakage: The first heap-dynamic variable is now inaccessible, or lost

⬥dangling pointer: a pointer that contains the address of a heap-dynamic variable that has been deallocated.

⬥eager approach(if count=0, retrieve immediately) VS lazy approach(if count=0, leave it and retreive later if short on memory)

⬥Casting(explicit type conversion) VS Coercion(implicit/automatic type conversion)

⬥strongly typed(make it compatible through casting=Java, C#) VS weakly typed(coersion=C)

⬥name type equivalance(stronger) VS structure type equivalence

⬥A data type defines a set of values and a collection of operations on those values. A type system is a set of types and the rules that govern their use in programs. Every typed programming language defines a type system.(p.317) 

Some important factors from "Concepts of Programming Languages (global edition) 11ed. - Robert W. Sebesta"

:Chapter 5

⬥6 attributes of variables: name, address, value, type, lifetime, and scope.

⬥Aliasing(3)

-C and C++ is with their union types

-when "call by reference," ==> actual/formal parameter have the same value

-two pointer variables have the same value

⬥static type binding VS dynamic type binding

(cf) disadvantage of dynamic type binding: type finding check X, high cost)

⬥storage bindings and lifetime

-static variables: global(non-local) variable / “static” local variable

-stack-dynamic variable: local variable

-explicit heap-dynamic variable

⬥purpose of functions: reuse(with modifications), process abstraction, information hiding

⬥static scope: functions are allowed nesting(eg.ALGOL60)

  However, C-based languages do not allow nested subprograms.

⬥referencing environment

-nesting O: local, global, non-local

-nesting X: local, global

⬥Named constants: useful aids to readability and program reliability

Some important factors from "Concepts of Programming Languages (global edition) 11ed. - Robert W. Sebesta"

:Chapter 3, 4

⬥context-free(one meaning for one lexeme) VS context-sensitive(one word having various meanings regarding the various situations)

⬥BNF(Backus–Naur form)

The derivation of the program from above is as follows:

<program> => begin <stmt_list> end
 => begin <stmt> ; <stmt_list> end
 => begin <var> = <expression> ; <stmt_list> end
 => begin A = <expression> ; <stmt_list> end
 => begin A = <var> + <var> ; <stmt_list> end
 => begin A = B + <var> ; <stmt_list> end
 => begin A = B + C ; <stmt_list> end
 => begin A = B + ; <stmt> end
 => begin A = B + C ; <var> = <expression> end
 => begin A = B + C ; B = <expression> end
 => begin A = B + C ; B = <var> end
 => begin A = B + C ; B = C end

(cf) Derivations that use this order of replacement are called leftmost derivations.

⬥Hierarchical structures are called parse trees.

From grammar of Example 3.2, through leftmost derivation, the following can be generated:

<assign> => <id> = <expr>
 => A = <expr>
 => A = <id> * <expr>
 => A = B * <expr>
 => A = B * ( <expr>)
 => A = B * ( <id> + <expr>)
 => A = B * ( A + <expr>)
 => A = B * ( A + <id>)
 => A = B * ( A + C )

Therefore, the following parse tree can be created:

There can be a unique parse tree or an ambiguous parse tree according to the grammar.

A unique parse tree will have an associativity of operaters(either lefts or right associativity)

⬥lexical analysis: find a lexeme --> add a token --> transfer to syntax analyzer

 + 3 more factors(s skipping comments and white space outside lexemes, create symbol table, error-detect)

⬥State transition diagram: similar to the finite automata from maths

⬥Parsing: top-down(preorder/recursive-descent parser, LL) VS bottom-up(postorder, LR)

⬥Syntax analysis purpose:

-check the input program to determine whether it is syntactically correct(=grammar checking)

-produce a complete parse tree(parsing)

Some important factors from "Concepts of Programming Languages (global edition) 11ed. - Robert W. Sebesta"

:Chapter 1, 2

⬥Reasons for studying concepts of programming languages

-Increased capacity to express ideas

-Improved background for choosing appropriate languages

-Increased ability to learn new languages.

⬥programming domains: scientific, business, artificial intelligence, web software

⬥cost: training programmers, writing / compiling / executing programs

⬥Computer Architecture

-machine codes consists of operator & operands

-von-Neumann: fetch->decode: fetch-execute(=instruction) cycle

-load, store, jump, ALU

⬥programming lagnauges are often cateogorized into four bins: imperative, functional, logic, object oriented

⬥Digitalizing Analgogues(2): 1.sampling 2.quantization

⬥3 ways of executing programs

: compilation, pure interpretation, hybrid implementation system(using the Just-In-Time compiler)

⬥intermediate code purpose

: code optimization, hardware platform independent, finding errors that have been missed while syntax analysis process