Python 3.6 - Points to remember

 

Points to remember

·         A variable is any location in the computer’s memory which holds a value.

·         Python is memory efficient when dealing with variables as compared to other programming languages.

·         An identifier is a name given to a variable, function, class, list, tuple etc. Identifiers are used to identify things in Python.

·         Keywords are reserved words in Python that have some special meaning and they can only be used for pre-defined purpose.

·         Comments are always used to describe the features of a program and ignored by Python compiler and interpreter.

·         ‘#’ symbol is used to create a single line comment.   

·         Python does not recommend Triple double quotes (“””) or triple single quotes (‘’’) as multi line comment.

·         If triple double quotes (“””) or triple single quotes (‘’’) are written as the first statement of a class, function, module etc., then they are called Docstrings and can be used to create API files.

·         Datatype represents the type of data such as int, float, str, list, tuple, dictionary etc.

·         There are two types of datatypes – built-in and user-defined. Datatypes that are already defined by Python team are called built-in and datatypes that are defined by user are called user-defined datatypes.

·          

Datatype

Characteristic

int

Immutable

float

Immutable

str (string)

Immutable

list

Mutable

tuple

Immutable

dictionary

Mutable

set

Mutable

range

Immutable

frozenset

Immutable

 

·         Conditions in Python internally evaluate to Boolean type i.e. True or False.

·         Indexing can be used to access a single element of a sequence at a time and slicing can be used to access a part or slice of sequence at a time.

·         Index in Python always starts from 0.

·         Reverse index always begins with -1.

·         Python does not support constants.  

·         The value stored into a variable is called literal.

·         A binary literal is represented using 0b or 0B in the beginning of a number.

·         An octal literal is represented using 0o or 0O in the beginning of a number.

·         A hexadecimal literal is represented using 0x or 0X in the beginning of a number.

·         We write strings in double or single quotes. And if a string spans more than one line then we can use triple single or triple double quotes.

·         A list is a collection of heterogeneous (different types of) elements and used to store large collection of data. List elements are written using square brackets [ ].

·         A tuple is similar to a list but tuple is immutable (elements cannot be modified) and can be created using parentheses ( ).

·         The range type is a collection or sequence of numbers and generally used with for loop. A range can be created using range( ) function.

·         A set is an unordered collection of elements and does not allow duplicate values. A set is created using curly braces { }.

·         We can use the type() function to determine the type of any object such as variable.

·         Python does not have concept of constants but you can write a constant name in all capital letters for your convenience.

·         Python has no datatype to represent single character.

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