Words of the trade

To avoid ambiguity we need a common vocabulary and a structured framework for communication.

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Structured commmunication

• An algorithm is writeable, unambiguous, completeable, and deterministic list of instructions, where

• Writeable means the description of the algortithm has finite length

• Unambiguous means the instructions are completely understandable

• Completeable means carrying out the instructions takes finite time

• Deterministic means whenever given the same inputs, the algorithms produces the same results.

• A program is an algorithm expressed in a programming language.

• In programming parlance, instructions are called statements.

• Synonyms for carrying out the instructions of a program are executing or running.

• Programming languages provide grammars (rules of structured communication) for producing syntactically correct (legal) code.

• Programming languages detail the specific actions to be taken (semantics) for each of its grammar rules.

• Style rules are (optional and legal) ways of writing code to support program reaability; e.g., snake_case.

• A program comment is an aside (explanation) to the reader. A comment is not program statement — there is no action associated with a comment other than to ignore it.

• A header comment identifies program user, purpose, and clarifications

• Whitespace is using horizontal or vertical spacing to separate different code elements; e.g., blank, tab, and indentation. Whitespace does not affect program interpretation.

• A compiler translates valid (i.e., syntactically correct) progamming language code (list of statements) from one language (source code) into another language (target code).

• An interpreter is a kind of compiler that carries out (executes) the statements as they are translated,

• A scripting language supports the automation of tasks in (special) run-time environments.

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Pythonics

• A Python interpreter verifies that the entire code file is syntactically correct before execution begins.

• A Python program is a list of statements written in Python executed one-at-a-time from top-to-bottom.

• A Python single-line comment begins with a # and continues for the rest of the line.

• A Python multi-line comment begins with a ''' and continues until another ''' is found.

• A literal is an explicit fundamental type value; e.g., 3, 1.4, 'dabchick', and True.

• An identifier is a symbolic name for a value or predefined action. A variable names mut be an identifier; i.e., a letter followed by zero or more letters and numbers).

• In an identifer, lettercase matters; e.g., email_id and Email_ID are different identifiers. Most seriously suggest do not have two identifiers whose only difference is lettercase.

• A program action is written as an expression. An expression is evaluated to determine the value it represents. Expressions are ubiquitous in Python.

• An assignment statement evaluates the expression to the left of the assignment operator = and assigns the variable to the right of the = that value.

• The arithmetic operators are +, -, *, \, \\, %, and ** and perform respectively addition, subtraction, multiplication, decimal division, integer division, remainder (modulus), and exponentiation.

• The relational operators are <, <=, >, >=, ==, and !=, and ** and perform respectively less than, less than or equal to, greater than, greater than or equal to, equality, and inequality comparisons.

• The logical operators are and, or, and not and perform respectively logical and, logical or, and logical negation

• A function is a named block of code.

• The print() function produces output to the program user.

• The print() function is one of many built-in (predefined) functions to support frequent programming tasks.

• A function invocation causes its block of code to be executed.

• A function invocation consists of the function name, parentheses, and within the parentheses a list of zero or more comma-separated values (arguments); e.g,. print() and print( 'ai' )).