Array length in Go - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the len() function do when used with an array in Go?

The len() function returns the number of elements in the array. It tells you how many items the array holds.

beginner

How do you declare an array of 5 integers in Go?

You write: var arr [5]int. This creates an array named arr that can hold exactly 5 integers.

beginner

If you have arr := [3]string{"a", "b", "c"}, what will len(arr) return?

It will return 3 because the array has 3 elements: "a", "b", and "c".

beginner

Can the length of an array in Go change after it is created?

No, the length of an array in Go is fixed when you declare it. You cannot add or remove elements to change its size.

intermediate

What is the difference between an array and a slice in Go regarding length?

An array has a fixed length known at compile time, while a slice is a flexible, dynamic view over an array and its length can change during runtime.

What does len(arr) return if arr := [4]int{1, 2, 3, 4}?

A 3

B Undefined

C 0

D 4

len() returns the number of elements in the array, which is 4 here.

Can you change the length of an array after it is declared in Go?

A No, arrays have fixed length

B Yes, by using <code>len()</code>

C Yes, by adding elements

D Only if the array is empty

Arrays in Go have a fixed length that cannot be changed after declaration.

Which Go type allows flexible length that can change during runtime?

A Slice

B Array

C Map

D Struct

Slices are dynamic and can grow or shrink, unlike arrays.

What is the output of len([3]string{"x", "y", "z"})?

A 1

B 3

C 0

D Error

The array has 3 elements, so len() returns 3.

How do you get the length of an array named numbers in Go?

A <code>numbers.length</code>

B <code>numbers.len()</code>

C <code>len(numbers)</code>

D <code>length(numbers)</code>

The correct way is to use the built-in function len().

Explain how to find the length of an array in Go and why the length is fixed.

Think about how arrays are declared and how len() works.

Describe the difference between an array and a slice in Go regarding their length and flexibility.

Consider how each type handles size changes.