Accessing array elements in Go - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an array in Go?

An array in Go is a fixed-size collection of elements of the same type, stored in contiguous memory locations.

beginner

How do you access the first element of an array named arr in Go?

You access it using arr[0] because Go arrays are zero-indexed, meaning the first element is at index 0.

intermediate

What happens if you try to access an array element with an index out of range in Go?

Go will cause a runtime panic with an 'index out of range' error, stopping the program.

beginner

Given var arr = [3]int{10, 20, 30}, what is the value of arr[2]?

The value is 30, because array indices start at 0, so arr[2] is the third element.

beginner

Can you change the value of an element in a Go array after it is created?

Yes, you can assign a new value to an element by accessing it with its index, like arr[1] = 50.

What is the index of the first element in a Go array?

A 1

B 0

C -1

D Depends on the array size

Go arrays start indexing at 0, so the first element is at index 0.

How do you access the third element of an array named nums?

A nums[2]

B nums[3]

C nums[1]

D nums[0]

Since indexing starts at 0, the third element is at index 2.

What happens if you try to access arr[5] in an array of length 3?

A Compiles but undefined behavior

B Returns zero value

C Returns last element

D Runtime panic: index out of range

Accessing an index outside the array length causes a runtime panic in Go.

Can you assign a new value to an existing element in a Go array?

A Yes, by using its index

B No, arrays are immutable

C Only if the array is a slice

D Only during array declaration

Go arrays allow changing element values by accessing them with their index.

Which of these is a valid way to declare an array of 4 integers in Go?

A arr := [4]int{1,2,3}

B var arr []int

C var arr [4]int

D arr := []int{1,2,3,4}

Option C declares a fixed-size array of 4 integers. Options B and D declare slices, and C has fewer elements than size.

Explain how to access and modify elements in a Go array.

Think about how you get and set values using the index.

Describe what happens if you try to access an array element outside its range in Go.

What does Go do to protect you from invalid access?