1. Strings¶

1.1. Printing strings¶

>>> print('Hello World!')
Hello World!

Or using double quotation mark

>>> print("Hello World!")
Hello World!

Note

Single ‘ quotation and Double ” quotation works almost same. But if you want to put ' into quotation mark you need to mix quotations characters ex.

>>> print("It's a nice day")
It's a nice day

But if you use ' twice you will see syntax exception

>>> print('It's a nice day')
Traceback (most recent call last):
SyntaxError: invalid syntax

1.2. Defining strings¶

txt = "Hello World!"
print(txt)

Hello World!

1.3. Checking types¶

>>> type(txt)
<class 'str'>

1.4. Checking length of string¶

>>> len(txt)
12

1.5. Printing special characters¶

New line special character

>>> print("Hello\nWorld!")
Hello
World!

Tabulator character

>>> print("Hello\tWorld!") 

1.6. String concatenation¶

>>> print('Hello ' +  'attendee')
Hello attendee

1.7. String concatenation - format¶

>>> print('Hello {}, have a great day'.format('Tomasz'))
Hello Tomasz, have a great day

1.8. Different representations - format¶

>>> '{:s}'.format('Some text') # in case of digit - exception
'Some text'

>>> '{:s}'.format(4) # in case of digit - exception
Traceback (most recent call last):
ValueError: Unknown format code 's' for object of type 'int

class Data:
    """Simple Data class"""

    def __init__(self, value):
        self.value = value

    def __str__(self):
        return '{}'.format(self.value)

    def __repr__(self):
        return '<{} object with value: {}>'.format(self.__class__.__name__, self.value)


print("{0!s}".format(Data(54), Data(54)))
print("{0!r}".format(Data(54), Data(54)))
print("{obj!s}".format(obj=Data(41)))
print("{obj!r}".format(obj=Data(41)))

54
<Data object with value: 54>
41
<Data object with value: 41>

>>> '{:>10}'.format('test')
'      test'

>>> '{:10}'.format('test')
'test      '

>>> '{:^10}'.format('test')
'   test   '

1.9. Functions available on srings¶

>>> 'Hello'.endswith('o')
True

>>> 'Hello'[-1] == 'o'
True

1.10. Substrings¶

>>> 'Hello'[-1]
'o'

>>> 'Hello'[0:6:2]
'Hlo'

names = 'Marta, Kasia, Monika, Tomek, Przemek, Janek, Marta, Malgosia'

print(names.count('Ma'))

In result we receive number of occurrences

Below we find an index of string.

>>> names.find('Kasia')
7

Hint

Letter ‘K’ is at 8th position, which means index no. 7 (countring from 0)

1.11. Splitting strings¶

>>> names.split(',')
['Marta', ' Kasia', ' Monika', ' Tomek', ' Przemek', ' Janek', ' Marta', ' Malgosia']

We received list of strings

1.12. Operations of strings¶

>>> names = names.replace("Janek", "Adam")
>>> print(names)
Marta, Kasia, Monika, Tomek, Przemek, Adam, Marta, Malgosia

1.13. Checking if string is a digit¶

>>> names.isdigit()
False

>>> temperature = "34"
>>> print(temperature.isdigit())
True

1.14. String as uppercase¶

>>> print(names.upper())
MARTA, KASIA, MONIKA, TOMEK, PRZEMEK, ADAM, MARTA, MALGOSIA

1.15. String as lowercase¶

>>> print(names.lower())
marta, kasia, monika, tomek, przemek, adam, marta, malgosia

1.16. Exercise¶

1 Create program writing your name and surname 2 Print fallowing statement: “Test characters: ‘, /, ” ” 3 Create two attendees of this training (give them names which you like) (both attendees are seperate variables)

first_attendee,

second_attendee

4 Exchange places of attendees - first_attendee should have second_attendee content and other way round

Print attendees,

Is it possible to change places in different way ?

5 Let user put his name using keyboard (Use google)