Slice creation in Go - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a slice in Go?

A slice is a flexible and dynamic view into the elements of an array. It allows you to work with sequences of elements without fixed size.

beginner

How do you create a slice with predefined elements in Go?

You can create a slice by listing elements inside square brackets without specifying size, like: slice := []int{1, 2, 3}.

intermediate

What does the built-in function make do when creating a slice?

make creates a slice with a specified length and capacity, for example: make([]int, 3, 5) creates a slice of length 3 and capacity 5.

intermediate

What is the difference between length and capacity of a slice?

Length is the number of elements the slice currently holds. Capacity is the total number of elements the slice can hold before needing to grow.

beginner

How do you create an empty slice in Go?

You can create an empty slice by declaring it without elements: var s []int or with make([]int, 0).

Which of the following creates a slice with 5 integers initialized to zero?

A make([]int, 5)

B []int{5}

C make([]int, 0, 5)

D var s [5]int

make([]int, 5) creates a slice of length 5 with zero values. Option B creates a slice with one element '5'. Option C creates a slice of length 0 but capacity 5. Option D creates an array, not a slice.

What is the length of the slice created by make([]string, 3, 10)?

A 3

B 10

C 0

D 13

The first number is the length, so the slice length is 3.

How do you declare a slice with elements 10, 20, and 30?

A slice := [3]int{10, 20, 30}

B slice := []int{10, 20, 30}

C slice := make([]int, 3)

D slice := []int(10, 20, 30)

Option B correctly creates a slice with those elements. Option C creates a slice of length 3 but with zero values. Option A creates an array, not a slice. Option D is invalid syntax.

What happens if you append an element to a slice that has reached its capacity?

A The element is ignored.

B The program crashes.

C The slice automatically grows to accommodate the new element.

D You must manually increase the capacity before appending.

Go automatically allocates a new underlying array with more capacity and copies elements when needed.

Which of these is NOT a valid way to create an empty slice?

A var s []int

B s := []int{}

C s := make([]int, 0)

D s := make([]int, 5)

Option D creates a slice of length 5, not empty. The others create empty slices.

Explain how to create a slice in Go with a specific length and capacity using the make function.

Think about the parameters make takes for slices.

Describe the difference between a slice's length and capacity and why it matters.

Consider what happens when you add elements beyond the current capacity.