How to insert a Character every X Characters in a String in Golang?

Question

Aim: to insert a character every x characters in a string in Golang

Input: helloworldhelloworldhelloworld

Expected Output: hello-world-hello-world-hello-world

Attempts

Attempt one

package main

import (
    "fmt"
    "strings"
)

func main() {
    s := "helloworldhelloworldhelloworld"

    s = strings.Replace(s, "world", ",", -1)
    fmt.Println(s)
}

results in: hello,hello,hello,

---

Attempt two

1. Count number of characters
2. For loop
3. If X=5 then insert a -

---

Attempt three

1. Scan combined with join

Problem

The reason that attempts two and three do not contain code snippets at the moment is that I am still thinking what approach should be used to insert a character every X characters in a string in Golang.

Answer 1

https://play.golang.org/p/HEGbe7radf

This function just inserts '-' each Nth element

func insertNth(s string,n int) string {
    var buffer bytes.Buffer
    var n_1 = n - 1
    var l_1 = len(s) - 1
    for i,rune := range s {
       buffer.WriteRune(rune)
       if i % n == n_1 && i != l_1  {
          buffer.WriteRune('-')
       }
    }
    return buffer.String()
}

Answer 2

I feel the following solution is worth mentioning:

package main

import "fmt"

var s = "helloworldhelloworldhelloworld"

func main() {
    for i := 5; i < len(s); i += 6 {
        s = s[:i] + "-" + s[i:]
    }
    fmt.Println(s)
}

https://play.golang.org/p/aMXOTgiNHf

Answer 3

According to the Go documentation strings are a read only Slice of bytes.. With that in mind there is an issue that comes up. What character set are you using? You can see some examples of where things get weird here and here.

Despite the complexity there still is a simple answer

s = strings.Replace(s, "hello", "hello-", -1)
s = strings.Replace(s, "world", "world-", -1)