Basics of Python

Code4tutorial basics of python
  • Python was created by Guido van Rossum in 1991 as a general-purpose programming language.
  • It is interpreted and interactive language. 
  • Python is an open-source language under a general public license (GPL). 
  • It supports both object-oriented and structured style of programming.


Features:
  • Cross-platform compatible: Python code can be executed on all platforms like Windows, Unix, Linux, and others.
  • Open-source language.
  • Supports both structured and object-oriented styles of programming.
  • wide range of libraries.
  • Provides interface required to connect all major databases like MySQL, Oracle, and Others 
Knowledge of the below basic concepts is a must before proceeding with the coding.
      • Identifiers 
      • Keywords
      • variables
      • datatypes
      • Input, output statements
      • Operators
      • Comments
1) Identifiers:
  • Identifiers are used to identify any variable, function, class, module, and object in python by using a name which is called an Identifier.
  • Identifiers are case-sensitive.
  • It can start with an uppercase or lowercase character or an underscore (_) followed by n number of underscores, letters, and digits.
      Example:  Number_1 = 50
                           Here Number_1 is an identifier
 
2) Keywords:
  • Keywords are reserved words in python.
  • These can't be used as an identifier to name a variable or function.
  • Some commonly used keywords are given below
    • if, elif, else, for, where, break, pass, continue, input
3) Variables:
  • Variables are used to hold the data which are like a container.
  • The value which the variable holds may not be the same throughout the program, it may change depends on the program logic.
  • Syntax: Variable_name = value
      Example: Number_1 = 50
 
       In the above example, Number_1 is a container(variable) that holds the value 50
 
4) Datatypes:
  • Every data belongs to some types. Commonly used data types are listed below
Category
Datatype
Example
Numeric
int
450
long
32321343535675687
Numeric with a decimal point
float
345.67
double
12453.5679873453
Alphanumeric
char
A
string
tutorials
Boolean
boolean
True, False

     1) Dynamical language - Python:

        Example: Number_1 = 50
    • In the above example, we didn't mention the data type at the time of declaring a variable but the python decides automatically based on the value which is assigned to it. This is called dynamic typing.
    • Examples:
      • Number_1 = 50  ---> Integer data type
      • Number_1 = 'ÁBC'  ---> String data type 
    • Try this CODE:
5.1) Input statement:
  • input() is a built-in function that is used to read input from the user using a standard input device (i.e., keyboard)
  • It always returns string data irrespective of what it receives from the user.
  • Syntax: Variable_name = input('Interactive Statement')
  • Example:
    • input_num = input("Enter the number:")
5.2) Output statement:
  • print() is a built-in function which is used to print the output on a standard output device (i.e., monitor)
  • Syntax: print(Variable_name)
  • Examples:
    • print(Number_1)
    • print("Hello")
6) Operators:
  • Operators are the symbols used to perform some operations on the program.
  • The most commonly used operators are listed below
Category 
Operators
Arithmetic Operators
+,-,*,/, %,//
Relational Operators
==,!=,>,<,>=,<=
Assignment Operators
=,+=,-=,*=,/=,%=
Logical Operators
and, or, not

7) Comments:
  • These are the lines that are skipped during the execution of the program.
  • There are two types of comments in python.
    • Single line comment: starts with the # symbol and extends till the end of the line.
    • Multi-line comment: starts with '' / ''' ends with ''/'''.
  • Mainly used for document purpose
  • Example:
    • Single line comment: #program to demonstrate the basics of python
    • Multi-line comment: ''''used for Demonstrating comment.''''
Let's see the basic concepts in detail in the next tutorial.

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