PROG LANGUAGES

Lexical analysis

involves reading the source code character from left to right

lexical analyzer

collects characters into logical groupings

regular expressions

In programming language, tokens can be described using what?

Input Preprocessing

Involves cleaning up the input text and preparing it for lexical analysis

Tokenization

Involves the process of breaking the input text into a sequence of tokens

Token Classification

The analyzer determines the type of each token

Token Validation

The analyzer checks if each token is valid based on the rules

Output Generation

The analyzer generates the output of the lexical analysis process,

Tokens

can be individual words or symbols in a sentence

Shift Operator

What is the name of this symbol? >>, < <, > > >

Logical

What is the name of this symbol? &&, |, ||, !

Comparison

What is the name of this symbol? ==, <, >,

Preprocessor

What is the name of this symbol? #

Logical Specifier

What is the name of this symbol? &

Punctuation

What is the name of this symbol? , and ;

Special Assignment

What is the name of this symbol? +=, -=, *=

Assignment

What is the name of this symbol? =

Lexemes

are the sequence of characters matched by a pattern to form the token

Non-tokens

What are these? Comments, preprocessor directive, macros, blanks, tabs, and new lines

27

How many tokens are there in this code:

int main() { int x = 15, y = 40; printf("sum is:%d", x + y); return 0; }

Syntax analysis, or parsing

is the process of analyzing a string of symbols

Syntax errors

are identified and flagged in this phase and must be corrected

syntax analyzer or parser

takes the token streams from a lexical analyzer and analyzes them against production rules

parse tree or Abstract Syntax Tree

is the output of this phase, representing the program’s structure

context-free grammar

syntax analysis uses this to define the syntax rules of a programming language

Parsing, Error Handling, Symbol Table Creation

Steps in a parser

Derivation

It is the process of applying the rules of Context-Free Grammar to generate a sequence of tokens

left-most derivation

if the sentential form of an input is scanned and replaced from left to right

right-most derivation

if the input is scanned and replaced with production rules

Parse Tree

It is the graphical representation of a derivation

Left-associative operations

include Addition, Multiplication, Subtraction, and Division

Right-associative operations

such as exponentiation will have the following evaluation in the same expression as above

1

What number of priority is this operator: ** or Exponentiation Operator

2

What number of priority is this operator:
Unary + and -

3

What number of priority is this operator:
*, / , //, %

4

What number of priority is this operator:
Binary + and -

name

is a string of characters used to identify some entity in a program

Java and C#

have no length limit, with all characters being significant

C++

does not specify length limits, but implementors sometimes do

PHP

All variable names in this Programming Language must begin with a dollar ($) sign

snake case

Use lowercase words. Separate words by underscores to improve readability

Pascal case

Start each word with a capital letter. Do not separate words with underscores

Special Words

These are used to make programs more readable by naming actions to be performed

reserved keyword

is a special word that cannot be used as a name in a programming language

Variables

is an abstraction of a computer memory cell or collection of cells

Variable Names

These are used to identify and reference values that can change

Variable Address

It acts as a numerical identifier that allows the program to access and manipulate the data

Variable Type

determines the range of values the variable can store

Variable Value

the contents of the memory cell or cells associated with the variable

Variable Lifetime

the amount of time it exists and retains its value in memory

Variable Scope

the part of the program where a variable can be accessed

Binding

is an association between an attribute and an entity

Binding time

is the time a binding takes place

explicit declaration

is a statement in a program that lists variable names

implicit declaration

is a means of associating variables with types through default conventions

static bindings

Both Explicit and Implicit declaration create this to types

binding

occurs when a value is assigned to a variable

Dynamic type binding

happens when the variable type is not specified

scope

is the range of statements wherein the variable is visible

Global Scope

Variables declared in this type of scope are accessible from anywhere in the program

Local Scope

Variables declared inside a function or block of code are local variables and can only be accessed within that specific function or block

Enclosing Scope

This refers to the scope of a function that encloses another function

Built-in Scope

contains all the functions and variables that are built into Python

LEGB Rule

Python follows this rule when looking up variables

Local, Enclosing, Global, Built-in

LEGB Stands for?

global keyword

In Python, to modify a global variable inside a function, it must be declared with what keyword