5.3. String Immutable

  • str is immutable

  • str methods create a new modified str

>>> text = 'Alice'
>>> result = text.upper()
>>>
>>> print(result)
ALICE
>>>
>>> print(text)
Alice

5.3.1. Memory

../../_images/type-str-memory-1.png
../../_images/type-str-memory-2.png
../../_images/type-str-memory-3.png
../../_images/type-str-immutable.png

5.3.2. Value Check

  • Use == to check if strings are equal

This is valid way to check str value:

>>> name = 'Alice'
>>>
>>> name == 'Alice'
True

5.3.3. Length

  • Builtin len() returns the length of a string

>>> len('Alice')
5

5.3.4. Concatenation

  • Preferred string concatenation is using f-string formatting

>>> 'alice' + '@' + 'example.com'
'alice@example.com'

>>> 'alice' '@' 'example.com'
'alice@example.com'

Line termination character \ is used to split long lines:

>>> result = 'alice' \
...          '@' \
...          'example.com'
>>>
>>> result
'alice@example.com'

>>> data = (
...     'alice'
...     '@'
...     'example.com'
... )
>>>
>>> data
'alice@example.com'

5.3.5. Concat Numbers

>>> name = 'Alice'
>>> age = 30
>>>
>>> 'User ' + name + ' has ' + str(age) + ' years'
'User Alice has 30 years'

>>> name = 'Alice'
>>> age = 30
>>>
>>> f'User {name} has {age} years'
'User Alice has 30 years'

5.3.6. Concat Multiply

>>> '*' * 10
'**********'