Iteration using range() in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the range() function do in Python?

The range() function generates a sequence of numbers, which is often used to repeat actions a certain number of times in loops.

beginner

How do you use range() to count from 0 to 4?

Use range(5). It creates numbers starting at 0 up to but not including 5, so 0, 1, 2, 3, 4.

intermediate

What are the three parameters of range() and what do they mean?

The three parameters are start (where to begin), stop (where to end, not included), and step (how much to jump each time). Example: range(1, 10, 2) counts 1, 3, 5, 7, 9.

intermediate

What happens if you use a negative step in range()?

Using a negative step makes the numbers count down. For example, range(5, 0, -1) counts 5, 4, 3, 2, 1.

beginner

Why is range() useful in a for loop?

range() tells the loop how many times to run by giving a sequence of numbers to go through. This helps repeat tasks easily without writing extra code.

What does range(3) produce?

A 3

B 1, 2, 3

C 0, 1, 2, 3

D 0, 1, 2

range(3) starts at 0 and goes up to but not including 3, so it produces 0, 1, 2.

Which range() call counts backwards from 5 to 1?

A range(1, 6, 1)

B range(5, 0, -1)

C range(5, 1)

D range(0, 5, -1)

range(5, 0, -1) starts at 5 and counts down by 1 until it reaches 1 (stop is not included).

What is the output of this code?<br>

for i in range(2, 7, 2): print(i)

A 2 3 4 5 6

B 2 4

C 2 4 6

D 2 3 5

The loop starts at 2, adds 2 each time, and stops before 7, so it prints 2, 4, 6.

What happens if you call range() with no arguments?

A It produces an error

B It produces an empty sequence

C It counts from 0 to 10

D It counts from 1 to 10

range() requires at least one argument; calling it without arguments causes an error.

Which of these is a valid way to use range()?

A range(1, 10, 3)

B range(5, 1, 1)

C range(0, 5, -1)

D range()

range(1, 10, 3) counts from 1 to 9 in steps of 3. The others produce empty sequences or an error.

Explain how to use range() in a for loop to repeat an action 5 times.

Think about how range creates numbers and how the loop uses them.

Describe the role of the start, stop, and step parameters in range().

Imagine walking on steps: where you start, where you stop, and how big your steps are.