A Quick Note on Python For Loops

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.

Looping Through a Sequence

You can loop through the items of any sequence.

# Looping through a list
fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(fruit)

# Looping through a string
for char in "banana":
    print(char)

The range() Function

To loop through a set of code a specified number of times, we can use the range() function.

for i in range(5):  # Looping from 0 to 4
    print(i)

The break Statement

With the break statement, we can stop the loop before it has looped through all the items.

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

The continue Statement

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

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

The else Statement

With the else statement, we can run a block of code once when the loop is finished.

for i in range(5):
    print(i)
else:
    print("Finally finished!")

Conclusion

The for loop is a powerful and versatile tool for iterating over sequences in Python. It provides a clean and readable way to process lists, strings, and other iterable objects. By using break, continue, and else, you can control the flow of your loops with great precision. Mastering the for loop is a crucial step in becoming a proficient Python programmer.