2.2. Syntax Print

2.2.1. String

  • Either quotes (") or apostrophes (') will work

  • Pick one and be consistent

  • Do not mix - str opening and closing characters must be the same

Either quotes (") or apostrophes (') will work. This topic will be covered in depth while talking about string type.

>>> name = 'Mark'
>>> name = "Mark"

>>> name = "Mark'
Traceback (most recent call last):
SyntaxError: unterminated string literal (detected at line 1)

>>> name = 'Mark"
Traceback (most recent call last):
SyntaxError: unterminated string literal (detected at line 1)

2.2.2. String Interpolation

  • String interpolation will substitute variable

  • F-string were introduced in Python 3.6

  • str.format() exists since Python 3.0

  • %-string is old (legacy) style from Python 1 and 2 era

  • More information in String Literals

>>> name = 'Mark'
>>> result = 'Hello {name}'
>>> result
'Hello {name}'

F-string (preferred):

>>> name = 'Mark'
>>> result = f'Hello {name}'
>>> result
'Hello Mark'

String format (legacy):

>>> name = 'Mark'
>>> result = 'Hello {}'.format(name)
>>> result
'Hello Mark'

>>> name = 'Mark'
>>> result = 'Hello {0}'.format(name)
>>> result
'Hello Mark'

>>> name = 'Mark'
>>> result = 'Hello {x}'.format(x=name)
>>> result
'Hello Mark'

%-format (legacy):

>>> name = 'Mark'
>>> result = 'Hello %s' % name
>>> result
'Hello Mark'

2.2.3. Print

  • Prints on the screen

  • Print string

  • Print variable

  • Print formatted (interpolated) string

  • More information in Builtin Printing

Print string:

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

Print variable:

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

Print interpolated string:

>>> name = 'Mark'
>>> print('Hello {name}')
Hello {name}

>>> name = 'Mark'
>>> print(f'Hello {name}')
Hello Mark

2.2.4. End of Lines

  • No semicolon (;) at the end of lines

  • Use \n for newline

  • Do not add space after \n character

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

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

>>> print('Hello\n World')
Hello
 World

2.2.5. Assignments

Code 2.6. assignments/syntax_print_a.py
"""
* Assignment: Syntax Print Newline
* Complexity: easy
* Lines of code: 1 lines
* Time: 2 min

English:
    1. Define `result` with text 'Hello World'
    2. 'Hello' must be in a first line
    3. 'World' must be in a second line
    4. Run doctests - all must succeed

Polish:
    1. Zdefiniuj zmienną `result` z tekstem 'Hello World'
    2. 'Hello' ma być w pierwszej linii
    3. 'World' ma być w drugiej linii
    4. Uruchom doctesty - wszystkie muszą się powieść

Hints:
    * Either quotes (") or apostrophes (') will work

Tests:
    >>> import sys; sys.tracebacklimit = 0

    >>> assert result is not Ellipsis, \
    'Assign your result to variable `result`'
    >>> assert type(result) is str, \
    'Variable `result` has invalid type, should be str'
    >>> assert 'Hello' in result, \
    'Word `Hello` must be in the `result`'
    >>> assert '\\n' in result, \
    'Newline `\\n` must be in the `result`'
    >>> assert 'World' in result, \
    'Word `World` must be in the `result`'
"""

# with Hello and World in separate lines
# type: str
result = ...
Code 2.7. assignments/syntax_print_b.py
"""
* Assignment: Syntax Print Interpolation
* Complexity: easy
* Lines of code: 2 lines
* Time: 2 min

English:
    1. Define `result` with text 'Hello NAME'
    2. Insted `NAME` substitute "Mark Watney"
    3. To substitute use f-string notation and `{variable}`
    4. Run doctests - all must succeed

Polish:
    1. Zdefiniiuj `result` z tekstem 'Hello NAME'
    2. W miejsce `NAME` podstaw "Mark Watney"
    3. Do podstawienia użyj notacji f-string i `{variable}`
    4. Uruchom doctesty - wszystkie muszą się powieść

Hints:
    * Either quotes (") or apostrophes (') will work
    * Use f-string

Tests:
    >>> import sys; sys.tracebacklimit = 0

    >>> assert result is not Ellipsis, \
    'Assign your result to variable `result`'
    >>> assert type(result) is str, \
    'Variable `result` has invalid type, should be str'
    >>> assert 'Mark Watney' in result, \
    'Variable `result` does not contain string "Mark Watney"'
    >>> assert '{NAME}' not in result, \
    'You must use f-string'

    >>> result
    'Hello Mark Watney'
"""

NAME = 'Mark Watney'

# Define result with text: `Hello NAME`
# Variable NAME should be interpolated
# type: str
result = ...