Common slice operations in Go - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a slice in Go?

A slice in Go is a flexible, dynamically-sized view into the elements of an array. It provides access to a segment of an array and can grow or shrink as needed.

beginner

How do you append an element to a slice?

Use the built-in append function. For example: slice = append(slice, element) adds element to the end of slice.

intermediate

How can you remove an element at index i from a slice?

You can remove an element by slicing and combining parts: slice = append(slice[:i], slice[i+1:]...). This skips the element at index i.

beginner

What does slicing a slice like slice[a:b] do?

It creates a new slice referencing elements from index a up to but not including b. The original slice is not copied, just referenced.

intermediate

How do you copy elements from one slice to another?

Use the built-in copy function: copy(dest, src) copies elements from src to dest. It copies up to the smaller length of the two slices.

What happens when you append an element to a slice that has no extra capacity?

A A new underlying array is allocated with more capacity, and the slice points to it.

B The element is discarded because the slice is full.

C The program crashes with an error.

D The element replaces the last element in the slice.

When appending to a slice with no extra capacity, Go allocates a new array with more space and copies existing elements before adding the new one.

How do you get a slice of the first 3 elements of a slice named data?

A data[0:3]

B data[3:0]

C Both A and D

D data[:3]

Both data[0:3] and data[:3] return a slice of the first 3 elements.

Which function is used to copy elements from one slice to another?

A append

B copy

C slice

D move

The built-in copy function copies elements from a source slice to a destination slice.

How do you remove the element at index 2 from a slice named items?

A items = append(items[3:], items[:2]...)

B items = items[2:]

C items = items[:2]

D items = append(items[:2], items[3:]...)

Appending items[:2] and items[3:] skips the element at index 2, effectively removing it.

What is the length of a newly created slice with make([]int, 5, 10)?

A 5

B 10

C 0

D 15

The length is 5, which is the number of initialized elements. The capacity is 10, the total space allocated.

Explain how to add and remove elements from a slice in Go.

Think about how you can combine parts of the slice to exclude an element.

Describe what happens internally when you append an element to a slice that is already full.

Consider how Go manages memory for slices when they grow.