Loops for

A for loop is a fundamental control structure in Python that allows you to execute a block of code repeatedly for each element in an iterable. In this guide, we will explore how to use a for loop with the range() function, how to exit a loop prematurely using the break keyword, and how to skip specific iterations with the continue keyword.

Using a For Loop with range()

The range() function generates a sequence of numbers. In the following example, range(10) produces numbers from 0 to 9. The variable i automatically takes on each value in the sequence, and the loop prints each number:

for i in range(10):
    print("i is:", i)

Expected output:

i is: 0
i is: 1
i is: 2
i is: 3
i is: 4
i is: 5
i is: 6
i is: 7
i is: 8
i is: 9

You can customize the iteration by specifying a starting value in the range() function if you need the sequence to begin at a number other than 0.

Breaking Out of a Loop

By default, a for loop continues until it has gone through the entire sequence. However, if you want to stop the loop early based on a condition (for example, when i equals 2), you can combine an if statement with the break keyword.

Consider this standard loop without interruption:

for i in range(5):
    print("i is:", i)

Output:

i is: 0
i is: 1
i is: 2
i is: 3
i is: 4

Now, to exit the loop when i equals 2, modify the code as follows:

for i in range(5):
    if i == 2:
        break
    print("i is:", i)

Output:

i is: 0
i is: 1

When i becomes 2, the condition is met and the break statement terminates the loop immediately.

Skipping Iterations with continue

Sometimes, you may want to skip only the current iteration of a loop instead of terminating it completely. The continue keyword allows you to do just that by skipping the rest of the code inside the loop for that particular iteration and moving on to the next one.

In the following example, the iteration is skipped when i equals 2:

for i in range(5):
    if i == 2:
        continue
    print("i is:", i)

Output:

i is: 0
i is: 1
i is: 3
i is: 4

When the loop encounters i equal to 2, the continue statement causes Python to skip the print statement for that iteration.

Recap

Final Thoughts

For loops are essential for iterating over sequences and automating repetitive tasks in Python. By mastering the use of range(), break, and continue, you can write more efficient and cleaner code. Start practicing these concepts with hands-on exercises to reinforce your learning and boost your Python programming skills.

Happy coding!