Davrot at 16:05, 17 October 2025

2025-10-17T16:05:56Z

← Older revision		Revision as of 16:05, 17 October 2025
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	~~== The goal ==~~
	For what reason…		For what reason…

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	== for loop (the truth) ==		== for loop (the truth) ==
	~~{: .topic-optional}~~ This is an optional topic!		'''This is an optional topic!'''

	The for loop is not counting up itself. It uses the __iter__ & __next__ combo of a instance of a class or a generator via [https://docs.python.org/3/reference/simple_stmts.html#the-yield-statement yield].		The for loop is not counting up itself. It uses the __iter__ & __next__ combo of a instance of a class or a generator via [https://docs.python.org/3/reference/simple_stmts.html#the-yield-statement yield].
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	print(i)</syntaxhighlight>Output:<syntaxhighlight lang="python">(0, 10)		print(i)</syntaxhighlight>Output:<syntaxhighlight lang="python">(0, 10)
	(1, 11)		(1, 11)
	(2, 12)</syntaxhighlight>~~{: .topic-optional}~~ This is an optional topic!<syntaxhighlight lang="python">for i in enumerate(range(10, 13)):		(2, 12)</syntaxhighlight>'''This is an optional topic!'''<syntaxhighlight lang="python">for i in enumerate(range(10, 13)):
	print(i)		print(i)
	else:		else:
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	(2, 12)		(2, 12)
	*		*
	(2, 12)</syntaxhighlight>~~{: .topic-optional}~~ This is an optional topic!<syntaxhighlight lang="python">class ClassIterExample:		(2, 12)</syntaxhighlight>'''This is an optional topic!'''<syntaxhighlight lang="python">class ClassIterExample:
	counter: int		counter: int
	counter_max: int		counter_max: int

Davrot: Created page with " == The goal == For what reason… Questions to [mailto:davrot@uni-bremen.de David Rotermund] '''Logic blocks need to be indented. Preferable with 4 spaces!''' == [https://docs.python.org/3/reference/compound_stmts.html#the-for-statement The for statement] ==
The for statement is used to iterate over the elements of a sequence (such as a string, tuple or list) or other iterable object
=== With range() === for..."

2025-10-15T11:00:17Z

Created page with " == The goal == For what reason… Questions to [mailto:davrot@uni-bremen.de David Rotermund] '''Logic blocks need to be indented. Preferable with 4 spaces!''' == [https://docs.python.org/3/reference/compound_stmts.html#the-for-statement The for statement] == <blockquote>The for statement is used to iterate over the elements of a sequence (such as a string, tuple or list) or other iterable object</blockquote> === With range() === <syntaxhighlight lang="python">for..."

New page

== The goal ==
For what reason…

Questions to [mailto:davrot@uni-bremen.de David Rotermund]

'''Logic blocks need to be indented. Preferable with 4 spaces!'''

== [https://docs.python.org/3/reference/compound_stmts.html#the-for-statement The for statement] ==
<blockquote>The for statement is used to iterate over the elements of a sequence (such as a string, tuple or list) or other iterable object</blockquote>

=== With range() ===
<syntaxhighlight lang="python">for i in range(0, 3):
print(i)</syntaxhighlight>Output:<syntaxhighlight lang="python">0
1
2</syntaxhighlight>

=== [https://docs.python.org/3/library/stdtypes.html#ranges range()] ===
<syntaxhighlight lang="python">class range(stop)
class range(start, stop[, step])</syntaxhighlight>

=== With a list ===
<syntaxhighlight lang="python">for i in [0, "A", 7, "nom num"]:
print(i)</syntaxhighlight>Output:<syntaxhighlight lang="python">0
A
7
nom num</syntaxhighlight>

== The full statement ==
<syntaxhighlight lang="python">for_stmt ::= "for" target_list "in" starred_list ":" suite
["else" ":" suite]</syntaxhighlight>

== for loop (the truth) ==
{: .topic-optional} This is an optional topic!

The for loop is not counting up itself. It uses the __iter__ & __next__ combo of a instance of a class or a generator via [https://docs.python.org/3/reference/simple_stmts.html#the-yield-statement yield].

=== Class ===
<syntaxhighlight lang="python">class ClassIterExample:
counter: int
counter_max: int

def __init__(self):
self.counter = 8
self.counter_max = 12

def __iter__(self):
return self

def __next__(self):
if self.counter < self.counter_max:
self.counter += 1
else:
raise StopIteration

important_result: int = self.counter**2

return f"Element: {self.counter}", important_result

test_instance = ClassIterExample()

for i in test_instance:
print(i)</syntaxhighlight>Output:<syntaxhighlight lang="python">('Element: 9', 81)
('Element: 10', 100)
('Element: 11', 121)
('Element: 12', 144)</syntaxhighlight>

=== Generator yield ===
<syntaxhighlight lang="python">from typing import Generator

def do_more(min_value: int, max_value: int) -> Generator:
for index in range(min_value, max_value):
yield index**2

for i in do_more(min_value=3, max_value=8):
print(i)</syntaxhighlight>Output:<syntaxhighlight lang="python">9
16
25
36
49</syntaxhighlight>

== for loop – [https://docs.python.org/3/library/functions.html#enumerate enumerate] ==
<syntaxhighlight lang="python">enumerate(iterable, start=0)</syntaxhighlight>If you need the index of the element then you can use enumerate:<syntaxhighlight lang="python">for i in enumerate(range(10, 13)):
print(i)</syntaxhighlight>Output:<syntaxhighlight lang="python">(0, 10)
(1, 11)
(2, 12)</syntaxhighlight>{: .topic-optional} This is an optional topic!<syntaxhighlight lang="python">for i in enumerate(range(10, 13)):
print(i)
else:
print("*")
print(i)</syntaxhighlight>Output:<syntaxhighlight lang="python">(0, 10)
(1, 11)
(2, 12)
*
(2, 12)</syntaxhighlight>{: .topic-optional} This is an optional topic!<syntaxhighlight lang="python">class ClassIterExample:
counter: int
counter_max: int

def __init__(self):
self.counter = 8
self.counter_max = 12

def __iter__(self):
return self

def __next__(self):
if self.counter < self.counter_max:
self.counter += 1
else:
raise StopIteration

important_result: int = self.counter**2

return f"Element: {self.counter}", important_result

test_instance = ClassIterExample()

for i in enumerate(test_instance):
print(i)</syntaxhighlight>Output:<syntaxhighlight lang="python">(0, ('Element: 9', 81))
(1, ('Element: 10', 100))
(2, ('Element: 11', 121))
(3, ('Element: 12', 144))</syntaxhighlight>You see a tuple with the enumerate id as a first component and a second tuple as result from the iterator.

== [https://docs.python.org/3/reference/simple_stmts.html#the-break-statement break] ==
<blockquote>break may only occur syntactically nested in a for or while loop, but not nested in a function or class definition within that loop.</blockquote><blockquote>It terminates the nearest enclosing loop, skipping the optional else clause if the loop has one.</blockquote><blockquote>If a for loop is terminated by break, the loop control target keeps its current value.</blockquote><syntaxhighlight lang="python">break_stmt ::= "break"</syntaxhighlight><syntaxhighlight lang="python">for i in range(0, 5):
if i == 2:
break
print(i)</syntaxhighlight>Output:<syntaxhighlight lang="python">0
1</syntaxhighlight>

== [https://docs.python.org/3/reference/simple_stmts.html#the-continue-statement continue] ==
<blockquote>continue may only occur syntactically nested in a for or while loop, but not nested in a function or class definition within that loop. It continues with the next cycle of the nearest enclosing loop.</blockquote><syntaxhighlight lang="python">continue_stmt ::= "continue"</syntaxhighlight><syntaxhighlight lang="python">for i in range(0, 5):
if i == 2:
continue
print(i)</syntaxhighlight>Output:<syntaxhighlight lang="python">0
1
3
4</syntaxhighlight>

Flow Control: for-loop - Revision history

Davrot at 16:05, 17 October 2025