The for loop
- Python course
- Beginner
- Lesson 42/116
- 4 min
Learn to iterate over iterables with for.
The for loop
A for loop repeats a block for each item of a collection (list, string, range):
for letter in "abc":
print(letter)This prints 'a', 'b', 'c' on separate lines. The in keyword specifies the collection. The loop variable (letter) takes each item in turn.
The for loop ends when the collection is exhausted. This structure is the basic tool for repetitive tasks.
Looping over strings and lists
The for loop works on ordered collections like strings and lists. Each character of a string, each item of a list is a step:
for item in [10, 20, 30]:
print(item)
for char in "Hello":
print(char)You choose the loop variable name (item, char); a meaningful name makes code readable.
Practice Loop over a list
Assign numbers = [10, 20, 30]. Write for n in numbers: print(n).
Starter code
# for loopSample solution
numbers = [10, 20, 30]
for n in numbers:
print(n)Expected output
10 20 30
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 How many times does for x in [1, 2, 3]: print(x) run?
- 3 Correct answer
- 2
- 1
- 0
Explanation: The list has 3 items, so it runs 3 times.
2 Complete the for loop
for letter ____ "abc":
print(letter)for letter in "abc":
print(letter)Explanation: in specifies the collection.
3 Match the for concepts
| Term | Meaning |
|---|---|
for |
Loop |
in |
Collection |
item |
Loop variable |
: |
Opening a block |