Stride for custom step in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the stride(from:to:by:) function do in Swift?

It creates a sequence of values starting from a given number, going up to (but not including) another number, stepping by a custom amount each time.

intermediate

How is stride(from:through:by:) different from stride(from:to:by:)?

stride(from:through:by:) includes the end value in the sequence if it matches a step, while stride(from:to:by:) stops before reaching the end value.

beginner

Write a Swift code snippet using stride(from:to:by:) to print even numbers from 2 up to 10 (excluding 10).

for number in stride(from: 2, to: 10, by: 2) { print(number) } // Output: 2 4 6 8

intermediate

Can stride be used with negative steps? Give an example.

Yes, you can use negative steps to count down. Example: for number in stride(from: 10, to: 0, by: -2) { print(number) } // Output: 10 8 6 4 2

beginner

Why might you choose stride over a traditional for-in loop with a range?

Because stride lets you control the step size, including skipping numbers or counting backwards, which a simple range loop can't do directly.

What will stride(from: 1, to: 5, by: 2) produce?

A [1, 3, 5]

B [1, 3]

C [1, 2, 3, 4, 5]

D [2, 4]

The sequence starts at 1, steps by 2, and stops before 5, so it includes 1 and 3 only.

Which function includes the end value if it matches the step exactly?

A stride(from:to:by:)

B range(from:to:by:)

C stride(from:through:by:)

D range(from:through:by:)

stride(from:through:by:) includes the end value if it fits the stepping pattern.

What happens if you use a negative step with stride(from:to:by:) but the start is less than the end?

A It reverses the sequence

B It counts up normally

C It causes a runtime error

D It creates an empty sequence

If the step direction doesn't match the start and end order, the sequence is empty.

How would you print numbers from 10 down to 2 stepping by 2 using stride?

A stride(from: 10, to: 2, by: -2)

B stride(from: 10, to: 2, by: 2)

C stride(from: 2, to: 10, by: -2)

D stride(from: 2, to: 10, by: 2)

You need to start at 10, go down to 2, stepping by -2.

Which of these is NOT a valid use of stride in Swift?

A stride(from: 1, to: 5, by: 0)

B stride(from: 10, through: 0, by: -2)

C stride(from: 0, to: 10, by: 1)

D stride(from: 5, to: 15, by: 3)

Step size cannot be zero; it would cause an error.

Explain how to use stride to create a sequence with a custom step size and why it might be useful.

Think about how you count in steps bigger than 1 or backwards.

Describe the difference between stride(from:to:by:) and stride(from:through:by:) with examples.

One stops before the end, the other can include it.