5.1. String Str

str is a sequence of characters

5.1.1. Syntax

>>> data = ''
>>> data = 'hello'

5.1.2. Quotes or Apostrophes

Both quotes (") and apostrophes (') works the same
Choose one style and keep consistency in code
Python console prefers single quote (') character
It matters for doctest, which compares two outputs character by character

Both " and ' works the same

>>> a = 'It is Monty Python'
>>> b = "It is Monty Python"
>>>
>>> a == b
True

Python console prefers single quote (') character:

>>> data = 'It is Monty Python'
>>> data
'It is Monty Python'
>>>
>>> data = "It is Monty Python"
>>> data
'It is Monty Python'

Why we have both? It's better to use double quotes, when text has apostrophes. This is also a default the behavior of Python console, which prefers less escape characters:

>>> data = 'It\'s Monty Python'
>>> data
"It's Monty Python"
>>>
>>> data = "It's Monty Python"
>>> data
"It's Monty Python"

However HTML and XML uses double quotes to enclose attribute values, hence it's better to use single quotes for the string:

>>> data = '<a href="https://python3.info">Python Book</a>'
>>> data
'<a href="https://python3.info">Python Book</a>'
>>>
>>> data = "<a href=\"https://python3.info\">Python Book</a>"
>>> data
'<a href="https://python3.info">Python Book</a>'

Errors:

>>> data = 'It's Monty Python'
Traceback (most recent call last):
SyntaxError: unterminated string literal (detected at line 1)

>>> data = "<a href="https://python3.info">Python Book</a>"
Traceback (most recent call last):
SyntaxError: invalid syntax

5.1.3. Newline and Tab

\n - New line (ENTER)
\t - Horizontal Tab (TAB)

>>> data = 'Hello\nWorld'
>>> print(data)
Hello
World

>>> data = 'Hello\tWorld'
>>> print(data)  
Hello   World

5.1.4. Multiline Strings

""" - three quotes
''' - three apostrophes

If assigned to variable, it serves as multiline str otherwise it's a docstring:

>>> data = """Fist line
... Second line
... Third line"""

>>> data = '''Fist line
... Second line
... Third line'''

5.1.5. Longer Strings

brackets () or backslashes \ can be used to split long strings
after \ there can't be any other character, not even a space (!)

>>> data = (
...     'First part '
...     'Second part '
...     'Third part'
... )

>>> data = 'First part ' \
...        'Second part ' \
...        'Third part'

5.1.6. Escape Characters

\' - Single quote ' (escape in single quoted strings)
\" - Double quote " (escape in double quoted strings)
\\ - Backslash \ (to indicate, that this is not escape char)
More information in Builtin Printing
https://en.wikipedia.org/wiki/List_of_Unicode_characters

>>> data = 'Hello\\World'
>>> print(data)
Hello\World

>>> data = 'Hello \'World\''
>>> print(data)
Hello 'World'

>>> data = "Hello \"World\""
>>> print(data)
Hello "World"

5.1.7. Conversion

Builtin function str() converts argument to str

>>> str(1)
'1'

>>> str(1.0)
'1.0'

>>> str(True)
'True'

>>> str(None)
'None'

5.1.8. Unicode

More information in Intermediate -> Encoding -> Unicode

>>> text = 'Hello \U0001F600'
>>> print(text)
Hello 😀

>>> text = 'Hello 😀'
>>> print(text)
Hello 😀

Advanced:

>>> a = '\U0001F9D1'  # 🧑
>>> b = '\U0000200D'  # ''
>>> c = '\U0001F680'  # 🚀
>>>
>>> astronaut = a + b + c
>>> print(astronaut)
🧑‍🚀

5.1.9. Recap

str is a sequence of characters
Both quotes (") and apostrophes (') works the same
Choose one style and keep consistency in code
Python console prefers single quote (') character
Builtin function str() converts argument to str
brackets () or backslashes \ can be used to split long strings
after \ there can't be any other character, not even a space (!)
\n - New line (ENTER)
\t - Horizontal Tab (TAB)
\' - Single quote ' (escape in single quoted strings)
\" - Double quote " (escape in double quoted strings)
\\ - Backslash \ (to indicate, that this is not escape char)

Definition:

>>> text = 'It is Monty Python'
>>> text = "It is Monty Python"

Quotes or apostrophes:

>>> text = "It's Monty Python"
>>> text = 'It\'s Monty Python'
>>>
>>> text = '<a href="https://python3.info">Python Book</a>'
>>> text = "<a href=\"https://python3.info\">Python Book</a>"

Newline and Tab:

>>> text = 'Hello\nWorld'
>>> text = 'Hello\tWorld'

Multiline:

>>> text = """Fist line
... Second line
... Third line"""

>>> text = '''Fist line
... Second line
... Third line'''

Longer:

>>> text = (
...     'First part '
...     'Second part '
...     'Third part'
... )

>>> text = 'First part ' \
...        'Second part ' \
...        'Third part'

Type conversion:

>>> str(1)
'1'

Unicode:

>>> text = 'Hello \U0001F600'
>>> print(text)
Hello 😀

5.1.10. Assignments

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% About
# - Name: Type Str Define
# - Difficulty: easy
# - Lines: 1
# - Minutes: 2

# %% English
# 1. Define `result_a` with value `hello`, use single apostrophes
# 2. Define `result_b` with value `hello`, use single quotes
# 3. Run doctests - all must succeed

# %% Polish
# 1. Zdefiniuj `result_a` z wartością `hello`, użyj pojedynczych apostrofów
# 2. Zdefiniuj `result_b` z wartością `hello`, użyj pojedynczych cudzysłowów
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> assert result_a is not Ellipsis, \
'Assign your result to variable `result_a`'
>>> assert type(result_a) is str, \
'Variable `result_a` has invalid type, should be str'
>>> result_a
'hello'

>>> assert result_b is not Ellipsis, \
'Assign your result to variable `result_b`'
>>> assert type(result_b) is str, \
'Variable `result_b` has invalid type, should be str'
>>> result_b
'hello'
"""

# Define `result_a` with value `hello`, use single apostrophes
# type: str
result_a = ...

# Define `result_b` with value `hello`, use single quotes
result_b = ...

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% About
# - Name: Type Str Define
# - Difficulty: easy
# - Lines: 1
# - Minutes: 2

# %% English
# 1. Define `result_a` with value `hello`, use triple apostrophes
# 2. Define `result_b` with value `hello`, use triple quotes
# 3. Run doctests - all must succeed

# %% Polish
# 1. Zdefiniuj `result_a` z wartością `hello`, użyj potrójnych apostrofów
# 2. Zdefiniuj `result_b` z wartością `hello`, użyj potrójnych cudzysłowów
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> assert result_a is not Ellipsis, \
'Assign your result to variable `result_a`'
>>> assert type(result_a) is str, \
'Variable `result_a` has invalid type, should be str'
>>> result_a
'hello'

>>> assert result_b is not Ellipsis, \
'Assign your result to variable `result_b`'
>>> assert type(result_b) is str, \
'Variable `result_b` has invalid type, should be str'
>>> result_b
'hello'
"""

# Define `result_a` with value `hello`, use triple apostrophes
# type: str
result_a = ...

# Define `result_b` with value `hello`, use triple quotes
result_b = ...

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% About
# - Name: Type Str Quotes
# - Difficulty: easy
# - Lines: 1
# - Minutes: 2

# %% English
# 1. Define variable `result: str` with value:
#    He said: "It's Monty Python"
# 2. Run doctests - all must succeed

# %% Polish
# 1. Zdefiniuj zmienną `result: str` z wartością:
#    He said: "It's Monty Python"
# 2. Uruchom doctesty - wszystkie muszą się powieść

# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> from pprint import pprint

>>> assert result is not Ellipsis, \
'Assign your result to variable `result`'
>>> assert type(result) is str, \
'Variable `result` has invalid type, should be str'

>>> print(result)
He said: "It's Monty Python"
"""


# Define variable `result: str` with value:
# He said: "It's Monty Python"
# type: str
result = ...

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% About
# - Name: Type Str Unicode
# - Difficulty: easy
# - Lines: 1
# - Minutes: 2

# %% English
# 1. Define `result: str` with text: 'Hello 😀'
# 2. Unicode codepoint for smiley emoticon (😀) is '\U0001F600'
# 3. Run doctests - all must succeed

# %% Polish
# 1. Zdefiniuj `result: str` z tekstem: 'Hello 😀'
# 2. Kod znaku emotikony uśmieszek (😀) to '\U0001F600'
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> assert result is not Ellipsis, \
'Assign your result to variable `result`'
>>> assert type(result) is str, \
'Variable `result` has invalid type, should be str'

>>> '😀' in result
True
>>> result
'Hello 😀'
"""

# Define `result: str` with text: 'Hello 😀'
# Unicode codepoint for smiley emoticon (😀) is '\U0001F600'
# type: str
result = ...