Python for loop: The Complete Guide

For loop in Python is used for sequential traversal. It can iterate over the elements of any sequence, such as a list.   Loop continues until we reach the last element in the sequence.

Python for loop

Python for loop is used to iterate over the sequence either the list, a tuple, a dictionary, a set, or the string. Python for loop starts with a keyword “for” followed by an arbitrary variable name, which will hold the values of the following sequence object, which is stepped through.

The body of for loop is separated from the rest of the code using indentation. The for loops are traditionally used when you have a block of code in which you want to repeat a fixed number of times.

Syntax

The general syntax looks like the following code.

for <variable> in <sequence>:
	<statements>

Let us take a simple example of For Loop in Python.

# app.py

GoT = ['Daenerys', 'Jon', 'Tyrion']

for item in GoT:
    print(item)

See the output.

Python For Loop Example | How To Use Loops

In the above example, we have taken one list and iterated the list in the loop, and printed the item one by one.

Looping Through a String in Python

The strings are iterable objects; they contain the sequence of characters. Let us take the following example.

# app.py

name = 'KRUNAL'
for item in name:
    print(item)

See the output.

Looping Through a String in Python

The break Statement in Python

Using a break statement in the loop, we can stop it before it has looped through all the elements. See the below example.

# app.py

GoT1 = ['Daenerys', 'Jon', 'Tyrion']
for item1 in GoT1:
    print(item1)
    if item1 == 'Jon':
        break

In the above example, if the current iterable item equals Jon, it will break the loop. That is why we will not see the Tyrion logged in the console.

The break Statement in Python

Else in For Loop

The else keyword in the for loop specifies the code block to be executed when a loop is finished. 

If the else statement is used with the for loop, the else statement is performed when the loop has exhausted iterating the list.

# app.py

for x in range(5):
    print(x)
else:
    print('Executed Else Statement!!')

Output

Else in For Loop

Python range() Function

The range() function returns the sequence of numbers, starting from 0 by default, increasing by 1 by default, and ending at the specified number. We can generate the sequence of numbers using the range() function.

# app.py

for z in range(4):
      print(z)

Output

The range() Function in Python

Python continue Statement

With the help of the continue statement, we can stop the current iteration of the loop and continue with the next iteration.

# app.py

GoT2 = ['Daenerys', 'Jon', 'Tyrion']
for item2 in GoT2:
    if item2 == 'Jon':
        continue
    print(item2)

In the above example, when the current iterator is Jon, it will end the iteration and does not print the Jon in the console.

Output

The continue Statement in Python

Nested For loops in Python

The nested loop is a loop inside a loop. The “inner loop” will be executed once for each iteration of the “outer loop.” See the below demo.

# app.py

for x in color:
    for y in fruits:
        print(x, y)

Output

Nested For loops in Python

That’s it for this tutorial.

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