Python

• Variables in Python:

  • No declaration is required for variables
  • Variables must be initialized before use
• When an expression changes, Python associates a new object to the variable for referencing the value
• Variables can hold objects of different types as required
• Deleting variables:

  • Variables can be deleted using the del statement
• Data Types in Python:

  • Numbers:
  • Integers have no limit for value range
  • Integers can be represented in binary, octal, and hexadecimal systems
• Numbers:

  • Floating Point:
  • Float type designates floating-point numbers
  • Float values are represented with a decimal point
• Numbers:

  • Floating Point:
  • Scientific Notation:
  • The character e or E followed by a positive or negative integer can be used for scientific notation
• Numbers:

  • Complex Numbers:
  • Complex numbers are specified as <real part>+<imaginary part>j
• Boolean:

  • Python provides a Boolean data type with values True or False
• Strings in Python:

  • Strings can be represented in single (' ') or double (" ") quotes
  • Strings can contain as many characters as needed
• type() function:

  • Returns the class type of the argument passed
  • Mostly used for debugging purposes
• Arithmetic Operators:

  • Include addition, subtraction, multiplication, division, etc.
• Relational Operators:

  • Used for comparison, such as equal to, not equal to, greater than, etc.
• Logical Operators:

  • Include AND, OR, and NOT operators
• Bitwise Operators:

  • Used for manipulation of individual bits
• Identity Operators:

  • Compare memory locations of Python objects/variables
• Membership Operators:

  • Test if a value is a member of other Python objects like strings, lists, or tuples
• Type Conversion (Casting):

  • Implicit Type Casting
  • Explicit Type Casting
• References:

  • Various resources for further learning and understanding Python data types and operators
• Python Control Flow:

  • Apply different types of if statements in Python programs
  • Apply switcher statements in Python programs
  • Apply while and for loops in Python programs
  • Use range() function in Python programs
  • Use pass statement
• Conditional Statements:

  Simple if statement:

  • Used when checking only one condition
  • Syntax: if Expression:
  • Example:

  age=int(input("Enter the age:"))

  if age >= 60:

  print("You are a senior citizen")

  print("End of script")
• If...else statement:

  • Used when checking exactly 2 different conditions
  • Syntax: if Expression:
  • Example:

  age=int(input("Enter the age:"))

  if age >= 60:

  print("You are a senior citizen")

  else:

  print("You are not a senior citizen")

  print("End of script")
• If...elif...else statement:

  • Used when checking more than 2 conditions
  • Syntax: if Expression_1:
  • Example:

  age=int(input("Enter the age:"))

  if age<13:

  print("You are a child.")

  elif age>=13 and age<18:

  print("You are a teenager.")

  elif age>=18 and age<60:

  print("You are an adult.")

  else:

  print("You are a senior citizen.")

  print("End of script")
• Switcher statement:

  • The switch...case is not available in Python
  • Define a function to provide switcher
  • Example:

  def week(i):

  switcher={

  0:'Sunday',

  1. 'Monday',

  ...

  1. 'Saturday'

  }

  return switcher.get(i,"Invalid day of week")

  print(week(7))

  Output: Invalid day of week
• Python Loops:

  While loop:

  • Syntax: while (checking condition):
  • Example:

  sum = 0

  i=1

  while i <= n:

  sum=sum+i

  i += 1

  print("The sum of first",n,"terms=",sum)
• While...else loop:

  • Example:

  i = 1

  while i < 7:

  print(i)

  i += 1

  else:

  print("i is no longer less than 7")
• Range() function:

  • Returns a sequence of numbers starting from 0 by default
  • Syntax: range(start, end, increment)
  • Example:

  for i in range(1,6):

  for j in range(1,i+1):

  print("@",end=' ')

  print()
• A string in Python is a group of characters enclosed within single, double, or triple quotes
• Strings are a sequential collection of characters
• To create a string, the most commonly used syntax is double quotes
• Triple single or triple-double quotes are used when creating multiple lines of a string
• Inside a string, single and double quotes can be used
• String indexing in Python can be done using positive and negative indexing
• Positive indexing starts from 0 (zero) in the left to right direction
• Negative indexing starts from -1 (minus one) in the right to left direction
• String slicing in Python is used to access parts of a string
• Slicing indices should be integers or None, otherwise errors will occur
• The default value for the step in slicing is 1
• Strings in Python are immutable, meaning their state cannot be changed once created
• The + operator in Python is used for string concatenation