Mastering Python For Loops – A Comprehensive Tutorial

In Python, for loops are an essential tool for iterating over sequences, including lists, tuples, dictionaries, sets, and strings. Unlike many other programming languages that require manual control of indexing, Python’s for loop simplifies iteration using a clean and readable syntax.

Basic Loop Structure

With a for loop, you can execute a block of code once for each item in a collection.

fruits = ["apple", "banana", "cherry"]
for x in fruits:
    print(x)

No need to declare an indexing variable beforehand – Python handles it automatically.

Iterating Over Strings

Strings in Python are iterable objects, meaning you can loop through each character individually:

for x in "banana":
    print(x)

Using the break Statement

The break statement allows you to exit a loop prematurely:

fruits = ["apple", "banana", "cherry"]
for x in fruits:
    print(x)
    if x == "banana":
        break

Alternatively, stop the loop before printing:

for x in fruits:
    if x == "banana":
        break
    print(x)

Using the continue Statement

The continue statement skips the current iteration and proceeds to the next:

for x in fruits:
    if x == "banana":
        continue
    print(x)

The range() Function

range() generates a sequence of numbers and is frequently used for looping a specific number of times:

for x in range(6):
    print(x)

You can customize the start, end, and step size:

for x in range(2, 6):
    print(x)

for x in range(2, 30, 3):
    print(x)

Using else with Loops

An optional else block can execute after the loop completes—unless it’s interrupted by a break:

for x in range(6):
    print(x)
else:
    print("Finally finished!")

If break is used, the else block will not run:

for x in range(6):
    if x == 3:
        break
    print(x)
else:
    print("Finally finished!")

Nested Loops

Nested loops let you combine elements from multiple sequences:

adj = ["red", "big", "tasty"]
fruits = ["apple", "banana", "cherry"]

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

Handling Empty Loops with pass

To avoid syntax errors when a loop body is intentionally left empty, use the pass statement:

for x in [0, 1, 2]:
    pass

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