Delete an element from a slice by index

Directly deleting an element from a slice is not possible in Go. However, you can overwrite the element with later elements by using append.

s = append(s[:i], s[i+1:]...)

This should be read as: append “all elements that come after i” to “the elements up to i”.

Due to the way append works, this will not allocate a new backing array.

As a more concrete example, suppose you have the following food slice backed by array a.

a := [6]string{"", "🍎", "🍔", "🌭", "🍕", ""}
food := a[1:5]

To delete the element with index 1 (index 2 in the backing array) we would write the following code:

food = append(food[:1], food[2:])

If we diagram the steps taken, it would look like this:

Depending on your Go version there might already be a function that implements this code:

• In 1.21 and later, use the Delete function in the slices package in the standard library.
• For earlier versions, you can find the same function in the experimental slices package (also shown in the example below).

If you are using a Go version that does not support generics, you can always implement your own Delete function. See the example below:

package main

import (
	"fmt"
	"slices"
)

func main() {
	x := []string{"👁", "👃", "👁"}
	y := []string{"👁", "👃", "👁"}

	fmt.Println("x and y before", x, y)

	x = Delete(x, 1)
	y = slices.Delete(y, 1, 2)

	fmt.Println("x and y after", x, y)
}

func Delete(s []string, i int) []string {
	return append(s[:i], s[i+1:]...)
}