Open In App

For Loops in Python

Last Updated : 19 Jun, 2024
Improve
Improve
Like Article
Like
Save
Share
Report

The For Loops in Python are a special type of loop statement that is used for sequential traversal. Python For loop is used for iterating over an iterable like a String, Tuple, List, Set, or Dictionary. 

In Python, there is no C style for loop, i.e., for (i=0; I <n; i++). The For Loops in Python is similar to each loop in other languages, used for sequential traversals.

Flowchart of Python For Loop

For Loops in Python

For Loop flowchart

How to use the for loop in Python

In Python, the for loop is used to iterate over a sequence (such as a list, tuple, string, or dictionary) or any iterable object. The basic syntax of the for loop is:

Python For Loop Syntax

for var in iterable:
# statements

Note: In Python, for loops only implement the collection-based iteration.

Here we will see Python for loop examples with different types of iterables:

Python For Loop with String

This code uses a for loop to iterate over a string and print each character on a new line. The loop assigns each character to the variable i and continues until all characters in the string have been processed.

Python
# Iterating over a String
print("String Iteration")

s = "Geeks"
for i in s:
    print(i)

Output:

String Iteration
G
e
e
k
s

Python for loop with Range

This code uses a Python for loop with index in conjunction with the range() function to generate a sequence of numbers starting from 0, up to (but not including) 10, and with a step size of 2. For each number in the sequence, the loop prints its value using the print() function. The output will show the numbers 0, 2, 4, 6, and 8.

Python
for i in range(0, 10, 2):
    print(i)

Output :

0
2
4
6
8

Python for loop Enumerate

In Python, the enumerate() function is used with the for loop to iterate over an iterable while also keeping track of the index of each item.

Python
l1 = ["eat", "sleep", "repeat"]

for count, ele in enumerate(l1):
    print (count, ele)

Output

0 eat
1 sleep
2 repeat

Nested For Loops in Python

This code uses nested for loops to iterate over two ranges of numbers (1 to 3 inclusive) and prints the value of i and j for each combination of the two loops. The inner loop is executed for each value of i in the outer loop. The output of this code will print the numbers from 1 to 3 three times, as each value of i is combined with each value of j.

Python
for i in range(1, 4):
    for j in range(1, 4):
        print(i, j)

Output :

1 1
1 2
1 3
2 1
2 2
2 3
3 1
3 2
3 3

Python For Loop Over List

This code uses a for loop to iterate over a list of strings, printing each item in the list on a new line. The loop assigns each item to the variable I and continues until all items in the list have been processed.

Python
# Python program to illustrate
# Iterating over a list
l = ["geeks", "for", "geeks"]

for i in l:
    print(i)

Output :

geeks
for
geeks

Python for loop in One Line

Python
Numbers =[x for x in range(11)]
print(Numbers)

Output

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Python For Loop with Dictionary

This code uses a for loop to iterate over a dictionary and print each key-value pair on a new line. The loop assigns each key to the variable i and uses string formatting to print the key and its corresponding value.

Python
# Iterating over dictionary
print("Dictionary Iteration")

d = dict()

d['xyz'] = 123
d['abc'] = 345
for i in d:
    print("% s % d" % (i, d[i]))

Output:

Dictionary Iteration
xyz 123
abc 345

Python For Loop with Tuple

This code iterates over a tuple of tuples using a for loop with tuple unpacking. In each iteration, the values from the inner tuple are assigned to variables a and b, respectively, and then printed to the console using the print() function. The output will show each pair of values from the inner tuples.

Python
t = ((1, 2), (3, 4), (5, 6))
for a, b in t:
    print(a, b)

Output :

1 2
3 4
5 6

Python For Loop with Zip()

This code uses the zip() function to iterate over two lists (fruits and colors) in parallel. The for loop assigns the corresponding elements of both lists to the variables fruit and color in each iteration. Inside the loop, the print() function is used to display the message “is” between the fruit and color values. The output will display each fruit from the list of fruits along with its corresponding color from the colours list.

Python
fruits = ["apple", "banana", "cherry"]
colors = ["red", "yellow", "green"]
for fruit, color in zip(fruits, colors):
    print(fruit, "is", color)

Output :

apple is red
banana is yellow
cherry is green

Control Statements that can be used with For Loop in Python

Loop control statements change execution from their normal sequence. When execution leaves a scope, all automatic objects that were created in that scope are destroyed. Python supports the following control statements.

Continue in Python For Loop

Python continue Statement returns the control to the beginning of the loop.

Python
# Prints all letters except 'e' and 's'

for letter in 'geeksforgeeks':

    if letter == 'e' or letter == 's':
        continue
    print('Current Letter :', letter)

Output: 

Current Letter : g
Current Letter : k
Current Letter : f
Current Letter : o
Current Letter : r
Current Letter : g
Current Letter : k

Break in Python For Loop

Python break statement brings control out of the loop.

Python
for letter in 'geeksforgeeks':

    # break the loop as soon it sees 'e'
    # or 's'
    if letter == 'e' or letter == 's':
        break

print('Current Letter :', letter)

Output: 

Current Letter : e

For Loop in Python with Pass Statement

The pass statement to write empty loops. Pass is also used for empty control statements, functions, and classes.

Python
# An empty loop
for letter in 'geeksforgeeks':
    pass
print('Last Letter :', letter)

Output: 

Last Letter : s 

For Loops in Python with Else Statement

Python also allows us to use the else condition for loops. The else block just after for/while is executed only when the loop is NOT terminated by a break statement.

Python
# Python program to demonstrate
# for-else loop

for i in range(1, 4):
    print(i)
else:  # Executed because no break in for
    print("No Break\n")

Output: 

1
2
3
No Break

Python For Loop Exercise Questions

Below are two Exercise Questions on Python for-loops. We have covered continue statement and range() function in these exercise questions.

Q1. Code to implement Continue statement in for-loop

Python
clothes = ["shirt", "sock", "pants", "sock", "towel"]
paired_socks = []
for item in clothes:
    if item == "sock":
        continue
    else:
        print(f"Washing {item}")
paired_socks.append("socks")
print(f"Washing {paired_socks}")

Output

Washing shirt
Washing pants
Washing towel
Washing ['socks']

Q2. Code to implement range function in for-loop

Python
for day in range(1, 8):
    distance = 3 + (day - 1) * 0.5
    print(f"Day {day}: Run {distance:.1f} miles")

Output

Day 1: Run 3.0 miles
Day 2: Run 3.5 miles
Day 3: Run 4.0 miles
Day 4: Run 4.5 miles
Day 5: Run 5.0 miles
Day 6: Run 5.5 miles
Day 7: Run 6.0 miles

For Loops in Python – FAQs

What is the syntax of a for loop in Python?

The syntax of a for loop in Python is straightforward. It iterates over a sequence (like a list, tuple, string, etc.) and executes the block of code inside the loop for each element in the sequence.

for item in sequence:
# Code block to execute

How to iterate with an index in a for loop in Python?

You can use the ‘enumerate()’ function to iterate over a sequence and retrieve both the index and the value of each element.

for index, item in enumerate(sequence):
# Use index and item inside the loop

Can you provide examples of for loops in Python?

Sure! Here are some examples of for loops in Python:

# Example 1: Iterating over a list
fruits = ['apple', 'banana', 'cherry']
for fruit in fruits:
print(fruit)

# Example 2: Iterating over a string
for char in 'Python':
print(char)

# Example 3: Using enumerate to get index and value
for index, num in enumerate([10, 20, 30]):
print(f'Index {index}: {num}')

# Example 4: Iterating over a dictionary
person = {'name': 'John', 'age': 30}
for key, value in person.items():
print(f'{key}: {value}')

How to write a for loop in Python?

To write a for loop, specify the variable that will hold each item from the sequence (‘item’ in the examples above), followed by the keyword in and the sequence itself (‘sequence’ in the examples).

# Basic syntax
for item in sequence:
# Code block to execute

How to use for loops in Python?

For loops are used to iterate over sequences (like lists, tuples, strings, dictionaries) and perform operations on each element or key-value pair. They are fundamental for iterating and processing data in Python.

# Example: Calculating sum of numbers in a list
numbers = [1, 2, 3, 4, 5]
total = 0
for num in numbers:
total += num
print(f'Total sum: {total}')


Previous Article
Next Article

Similar Reads

Loops in Python - For, While and Nested Loops
Python programming language provides two types of Python loopshecking time. In this article, we will look at Python loops and understand their working with the help of examp - For loop and While loop to handle looping requirements. Loops in Python provides three ways for executing the loops. While all the ways provide similar basic functionality, t
9 min read
Loops and Control Statements (continue, break and pass) in Python
Python programming language provides the following types of loops to handle looping requirements. Python While Loop Until a specified criterion is true, a block of statements will be continuously executed in a Python while loop. And the line in the program that follows the loop is run when the condition changes to false. Syntax of Python Whilewhile
4 min read
Output of Python Programs | Set 22 (Loops)
Prerequisite: Loops Note: Output of all these programs is tested on Python3 1. What is the output of the following? mylist = ['geeks', 'forgeeks'] for i in mylist: i.upper() print(mylist) [‘GEEKS’, ‘FORGEEKS’]. [‘geeks’, ‘forgeeks’]. [None, None]. Unexpected Output: 2. [‘geeks’, ‘forgeeks’] Explanation: The function upper() does not modify a string
2 min read
Specifying the increment in for-loops in Python
Let us see how to control the increment in for-loops in Python. We can do this by using the range() function. range() function range() allows the user to generate a series of numbers within a given range. Depending on how many arguments the user is passing to the function, the user can decide where that series of numbers will begin and end as well
2 min read
How to make a box with the help of nested loops using Python arcade?
Arcade library is modern framework currently used in making 2D games. Nested loop discussed here are analogous to nested loops in any other programming language. The following tutorial will step by step explain how to draw a box with the help of nested loops using Python's arcade module. Import arcade library.Here we will be using circles to form a
2 min read
How to Break out of multiple loops in Python ?
In this article, we will see how to break out of multiple loops in Python. For example, we are given a list of lists arr and an integer x. The task is to iterate through each nested list in order and keep displaying the elements until an element equal to x is found. If such an element is found, an appropriate message is displayed and the code must
6 min read
Use for Loop That Loops Over a Sequence in Python
In this article, we are going to discuss how for loop is used to iterate over a sequence in Python. Python programming is very simple as it provides various methods and keywords that help programmers to implement the logic of code in fewer lines. Using for loop we can iterate a sequence of elements over an iterable like a tuple, list, dictionary, s
3 min read
Python Nested Loops
In Python programming language there are two types of loops which are for loop and while loop. Using these loops we can create nested loops in Python. Nested loops mean loops inside a loop. For example, while loop inside the for loop, for loop inside the for loop, etc. Python Nested Loops Syntax: Outer_loop Expression: Inner_loop Expression: Statem
7 min read
Python Do While Loops
In Python, there is no construct defined for do while loop. Python loops only include for loop and while loop but we can modify the while loop to work as do while as in any other languages such as C++ and Java. In Python, we can simulate the behavior of a do-while loop using a while loop with a condition that is initially True and then break out of
3 min read
Output of Python program | Set 15 (Loops)
Prerequisite - Loops in Python Predict the output of the following Python programs. 1) What is the output of the following program? x = ['ab', 'cd'] for i in x: i.upper() print(x) Output: ['ab', 'cd'] Explanation: The function upper() does not modify a string in place, but it returns a new string which here isn’t being stored anywhere. So we will g
2 min read
Practice Tags :
three90RightbarBannerImg