Python object class

• Every object in python is derived from the class object
• Writing the class in the below fashion

class Dummy:
    pass

is equal to

class Dummy(object):
    pass

• Now if we create an object, we can access methods of class object

class Dummy:
    pass


d = Dummy()
d.__str__()

• In the above __ str() __is method defined in object class

Strings in python

• You can create a python string by enclosing sequence of character in single or double quotes
• Strings in python3 are unicode
• Launch python shell

# in both the cases type will be str
course = "python"
type(course)
course = 'python'
type(course)

• Refer Here
• Single quotes can be used to enclose double quoted messages/text and vice versa
• There are some special strings is in python
  • f-string: They are used for formatting

  name = "Python"
  print(f"name is {name} ")
  

  • raw strings: The start with r or R
  • unicode string: This is default string
  • bytes
  • Multiline string: Will have triple quotes

  message = '''
      Hello how are you doing
      This is a special message to you
      Wish you a good luck
  '''
  print(message)
  

• Empty strings in python:
• Creating a string with str()
• Escape Sequences
  • \n
  • \t
  • \
  • "

String Operations

• Combine strings using +
• Duplicate strings with *
• Get a character at a specific position using []
• replace strings with replace() method
• Getting substrings with slicing operators
  • [:] extracts the entire sequence from start to end
  • [start:] specifies to extract from start offset to end
  • [:end] specifies to extract from start to end offset minus 1
  • [start:end]
  • [start:end:step]
• Get length using len()
• Splitting strings with split()
• Some other operations
• Casing methods
  • capitalize()
  • title()
  • upper()
  • lower()
  • swapcase()

String formatting

• For formatting strings in python there are three ways
  • old style
  • new style
  • f-strings

Old Style string formatting

• This formatting uses conversion types
  • %s: string
  • %d: decimal integer
  • %x: hex integer
  • %o: octal integer
  • %f: float
  • %e: exponential
  • %%: a literal %

movie = "Avengers"
character_liked = "ironman"
rating = 5
"I have watched %s and i liked %s character in the movie. I would like to %d as rating" % (movie, character_liked, rating)