Slicing 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 lets you work with parts of an array without copying data.

beginner

How do you create a slice from an array or another slice?

You use the slicing syntax: slice := array[start:end]. This creates a new slice from index start up to but not including end.

beginner

What happens if you omit the start or end index in a slice operation?

If you omit start, it defaults to 0 (start of the array). If you omit end, it defaults to the length of the array or slice.

intermediate

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

Length is how many elements the slice currently holds. Capacity is how many elements the slice can hold before it needs to grow (based on the underlying array).

intermediate

How can slicing affect the original array?

Slices share the same underlying array. Changing an element in a slice changes the same element in the original array and other slices sharing it.

What does arr[2:5] return if arr is a slice?

A Elements from index 3 to 5

B Elements from index 2 up to and including 5

C Elements from index 0 to 5

D Elements from index 2 up to but not including 5

Slicing in Go includes the start index but excludes the end index.

What is the length of the slice created by slice := arr[:]?

A Length of arr

B 0

C Capacity of arr

D Undefined

Omitting start and end means the slice includes the whole array, so length equals the array's length.

If you change an element in a slice, what happens to the original array?

A The original array changes at that element

B The original array stays the same

C A new array is created

D The slice becomes invalid

Slices share the underlying array, so changes affect the original array.

What does the capacity of a slice represent?

A Number of slices created from the array

B Current number of elements in the slice

C Maximum number of elements the slice can hold before resizing

D Size of the underlying array

Capacity is how many elements the slice can hold before it needs to allocate a new underlying array.

Which of these is a valid way to create a slice from an array arr?

A slice := arr(1,4)

B slice := arr[1:4]

C slice := arr[1..4]

D slice := arr.slice(1,4)

Go uses the syntax arr[start:end] for slicing.

Explain how slicing works in Go and how it relates to the underlying array.

Think about how slices are views into arrays, not copies.

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

Consider what happens when you append elements to a slice.