Golang : Delete duplicate items from a slice/array

Problem :

Fairly common question or task that a programmer will face from time to time. How to remove duplicate items in a slice ?

For example, this slice has 2 string duplicates :

 duplicate := []string{"Hello", "World", "GoodBye", "World", "We", "Love", "Love", "You"}

Solution :

Iterate over the slice and copy over the non duplicate items to a new slice.

 package main

 import (

 func printslice(slice []string) {
  fmt.Println("slice = ", slice)
  //for i := range slice {
 //  fmt.Println(i, slice[i])

 func stringInSlice(str string, list []string) bool {
  for _, v := range list {
 if v == str {
 return true
  return false

 func main() {
  duplicate := []string{"Hello", "World", "GoodBye", "World", "We", "Love", "Love", "You"}


  //need to delete duplicate data from slice
  // the idea is to copy data over to a new slice without the duplicate

  cleaned := []string{}

  for _, value := range duplicate {

 if !stringInSlice(value, cleaned) {
 cleaned = append(cleaned, value)


Output :

slice = [Hello World GoodBye World We Love Love You]

slice = [Hello World GoodBye We Love You]

NOTE : I'm sure there are more efficient solution out there. But for simple task with small set of data. This solution should be sufficient.

  See also : Golang : automatically figure out array length(size) with three dots

By Adam Ng

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