How do I reverse sort a slice of integer Go?

I am trying to reverse-sort a slice of integers in Go.

 example := []int{1,25,3,5,4} sort.Ints(example) // this will give me a slice sorted from 1 to the highest number 

How do I sort it so that it goes from highest to lowest? so [25 5 4 3 1]

I have tried this

sort.Sort(sort.Reverse(sort.Ints(keys))) 

Source:

However, I am getting the error below

# command-line-arguments ./Roman_Numerals.go:31: sort.Ints(keys) used as value 

3 Answers

sort.Ints is a convenient function to sort a couple of ints. Generally you need to implement the sort.Interface interface if you want to sort something and sort.Reverse just returns a different implementation of that interface that redefines the Less method.

Luckily the sort package contains a predefined type called IntSlice that implements sort.Interface:

keys := []int{3, 2, 8, 1} sort.Sort(sort.Reverse(sort.IntSlice(keys))) fmt.Println(keys) 

package main import ( "fmt" "sort" ) func main() { example := []int{1, 25, 3, 5, 4} sort.Sort(sort.Reverse(sort.IntSlice(example))) fmt.Println(example) } 

Playground

Output:

[25 5 4 3 1] 

Instead of using two function calls and a cast, you can do it with just sort.Slice:

package main import ( "fmt" "sort" ) func main() { example := []int{1,25,3,5,4} sort.Slice(example, func(a, b int) bool { return example[b] < example[a] }) fmt.Println(example) }