One-liner to transform []int into string

Basically I have []int{1, 2, 3}, I want a one-liner that transforms this into the string "1, 2, 3" (I need the delimiter to be custom, sometimes ., sometimes ,, etc). Below is the best I could come up with. Searched online and did not seem to find a better answer.

In most languages there is in-built support for this, e.g.:

python:

> A = [1, 2, 3]
> ", ".join([str(a) for a in A])
'1, 2, 3'

go:

package main

import (
    "bytes"
    "fmt"
    "strconv"
)

// Could not find a one-liner that does this :(.
func arrayToString(A []int, delim string) string {

    var buffer bytes.Buffer
    for i := 0; i < len(A); i++ {
        buffer.WriteString(strconv.Itoa(A[i]))
        if i != len(A)-1 {
            buffer.WriteString(delim)
        }
    }

    return buffer.String()
}

func main() {
    A := []int{1, 2, 3}
    fmt.Println(arrayToString(A, ", "))
}

Surely there must be an utility buried into go that allows me to do this with a one-liner?

I know that there is strings.Join(A, ", "), but that only works if A is already []string.

To convert
A := []int{1, 2, 3, 4, 5, 6, 7, 8, 9}

to a one line delimited string like
"1,2,3,4,5,6,7,8,9"
use:

strings.Trim(strings.Join(strings.Fields(fmt.Sprint(A)), delim), "[]")

or:

strings.Trim(strings.Join(strings.Split(fmt.Sprint(A), " "), delim), "[]")

or:

strings.Trim(strings.Replace(fmt.Sprint(A), " ", delim, -1), "[]")

and return it from a function such as in this example:

package main

import "fmt"
import "strings"

func arrayToString(a []int, delim string) string {
	return strings.Trim(strings.Replace(fmt.Sprint(a), " ", delim, -1), "[]")
	//return strings.Trim(strings.Join(strings.Split(fmt.Sprint(a), " "), delim), "[]")
	//return strings.Trim(strings.Join(strings.Fields(fmt.Sprint(a)), delim), "[]")
}

func main() {
	A := []int{1, 2, 3, 4, 5, 6, 7, 8, 9}

	fmt.Println(arrayToString(A, ",")) //1,2,3,4,5,6,7,8,9
}

To include a space after the comma you could call arrayToString(A, ", ") or conversely define the return as return strings.Trim(strings.Replace(fmt.Sprint(a), " ", delim + " ", -1), "[]") to force its insertion after the delimiter.

I've just run into the same problem today, since I've not found anything on standard library, I've recompiled 3 ways to do this conversion

Create a string and appending the values from the array by converting it using strconv.Itoa:

func IntToString1() string {
	a := []int{1, 2, 3, 4, 5}
	b := ""
	for _, v := range a {
		if len(b) > 0 {
			b += ","
		}
		b += strconv.Itoa(v)
	}

	return b
}

Create a []string, convert each array value and then return a joined string from []string:

func IntToString2() string {
	a := []int{1, 2, 3, 4, 5}
	b := make([]string, len(a))
	for i, v := range a {
		b[i] = strconv.Itoa(v)
	}

	return strings.Join(b, ",")
}

Convert the []int to a string and replace / trim the value:

func IntToString3() string {
	a := []int{1, 2, 3, 4, 5}
	return strings.Trim(strings.Replace(fmt.Sprint(a), " ", ",", -1), "[]")
}

Performance is quite different depending on implementation:

BenchmarkIntToString1-12         3000000           539 ns/op
BenchmarkIntToString2-12         5000000           359 ns/op
BenchmarkIntToString3-12         1000000          1162 ns/op

Personally, I'll go with IntToString2, so the final function could be an util package in my project like this:

func SplitToString(a []int, sep string) string {
    if len(a) == 0 {
	    return ""
    }

	b := make([]string, len(a))
	for i, v := range a {
		b[i] = strconv.Itoa(v)
	}
	return strings.Join(b, sep)
}

You can always json.Marshal:

data := []int{1,2,3}
s, _ := json.Marshal(data)
fmt.Println(string(s))
// output: [1, 2, 3]

fmt.Println(strings.Trim(string(s), "[]"))
//output 1,2,3

I believe that you can go with the fmt.Sprint family of functions. I am not expert in go formatting flags, and maybe you can make it with just a Sprintf, but here's a one-liner that works:

data := []int{1,2,3}

func(x string) string { return x[6:len(x)-1]; }(fmt.Sprintf("%#v", data)) // 1, 2, 3

In general, you could use strings.Replace to come up with different separators (as long as you can safely replace the , or default separator):

// Produces 1--2--3
magic := func(s, d string) string { return strings.Replace(s[1:len(s)-1], " ", d, -1)  }
fmt.Println(magic(fmt.Sprint([]int{1, 2, 3}), "--"))

// As one liner
fmt.Println(func(s, d string) string { return strings.Replace(s[1:len(s)-1], " ", d, -1)  }(fmt.Sprint([]int{1, 2, 3}), "--"))

    func convertIntToString(elems []int) string {
        b := ""
        for _, v := range elems {
	       b += strconv.Itoa(v)
	       b += ";"
        }
        return b
    }