Difference between revisions of "For loop in Python"
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With the for loop we can execute a set of statements, once for each item in a list, tuple, set etc. | With the for loop we can execute a set of statements, once for each item in a list, tuple, set etc. | ||
+ | |||
+ | Example | ||
+ | Print each fruit in a fruit list: | ||
+ | |||
+ | '''The for loop does not require an indexing variable to set beforehand.''' | ||
+ | |||
+ | <syntaxhighlight lang="Python"> | ||
+ | fruits = ["apple", "banana", "cherry"] | ||
+ | for x in fruits: | ||
+ | print(x) | ||
+ | </syntaxhighlight> | ||
+ | |||
+ | Looping Through a String | ||
+ | |||
+ | Even strings are iterable objects, they contain a sequence of characters: | ||
+ | |||
+ | <syntaxhighlight lang="Python"> | ||
+ | for x in "banana": | ||
+ | print(x) | ||
+ | </syntaxhighlight> | ||
+ | |||
+ | |||
+ | '''The range() Function''' | ||
+ | |||
+ | To loop through a set of code a specified number of times, we can use the range() function, | ||
+ | The range() function returns a sequence of numbers, starting from 0 by default, and increments by 1 (by default), and ends at a specified number. | ||
+ | |||
+ | Example | ||
+ | |||
+ | Using the range() function: | ||
<syntaxhighlight lang="Python"> | <syntaxhighlight lang="Python"> | ||
+ | for x in range(6): | ||
+ | print(x) | ||
+ | </syntaxhighlight> | ||
+ | |||
+ | Note that range(6) is not the values of 0 to 6, but the values 0 to 5. | ||
+ | |||
+ | The range() function defaults to 0 as a starting value, however, it is possible to specify the starting value by adding a parameter: | ||
+ | range(2, 6), which means values from 2 to 6 (but not including 6): | ||
+ | |||
+ | <syntaxhighlight lang="Python"> | ||
+ | for x in range(2, 6): | ||
+ | print(x) | ||
+ | </syntaxhighlight> | ||
+ | |||
+ | |||
+ | The range() function defaults to increment the sequence by 1, | ||
+ | however it is possible to specify the increment value by adding a third parameter: range(2, 30, 3): | ||
+ | |||
+ | Example | ||
+ | |||
+ | Increment the sequence with 3 (default is 1): | ||
+ | <syntaxhighlight lang="Python"> | ||
+ | for x in range(2, 30, 3): | ||
+ | print(x) | ||
+ | </syntaxhighlight> | ||
+ | |||
+ | |||
+ | |||
+ | <syntaxhighlight lang="Python"> | ||
+ | </syntaxhighlight> | ||
------------------- | ------------------- | ||
source: https://www.w3schools.com/python/python_for_loops.asp | source: https://www.w3schools.com/python/python_for_loops.asp |
Revision as of 14:23, 28 August 2024
A for loop is used for iterating over a sequence (that is either a list, a tuple, a dictionary, a set, or a string).
This is less like the for keyword in other programming languages, and works more like an iterator method as found in other object-orientated programming languages.
With the for loop we can execute a set of statements, once for each item in a list, tuple, set etc.
Example
Print each fruit in a fruit list:
The for loop does not require an indexing variable to set beforehand.
fruits = ["apple", "banana", "cherry"]
for x in fruits:
print(x)
Looping Through a String
Even strings are iterable objects, they contain a sequence of characters:
for x in "banana":
print(x)
The range() Function
To loop through a set of code a specified number of times, we can use the range() function, The range() function returns a sequence of numbers, starting from 0 by default, and increments by 1 (by default), and ends at a specified number.
Example
Using the range() function:
for x in range(6):
print(x)
Note that range(6) is not the values of 0 to 6, but the values 0 to 5.
The range() function defaults to 0 as a starting value, however, it is possible to specify the starting value by adding a parameter: range(2, 6), which means values from 2 to 6 (but not including 6):
for x in range(2, 6):
print(x)
The range() function defaults to increment the sequence by 1, however it is possible to specify the increment value by adding a third parameter: range(2, 30, 3):
Example
Increment the sequence with 3 (default is 1):
for x in range(2, 30, 3):
print(x)
source: https://www.w3schools.com/python/python_for_loops.asp