Python Classroom Series – 02/Sept/2020

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 Preview
  • 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: Preview
  • Creating a string with str() Preview
  • Escape Sequences
    • \n
    • \t
    • \
    • " Preview

String Operations

  • Combine strings using +
  • Duplicate strings with * Preview
  • Get a character at a specific position using [] Preview
  • replace strings with replace() method Preview
  • 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] Preview
  • Get length using len()
  • Splitting strings with split() Preview
  • Some other operations Preview
  • Casing methods
    • capitalize()
    • title()
    • upper()
    • lower()
    • swapcase() Preview

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)

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