How to merge multiple strings and int into a single string

Question

I am a newbie in Go. I can't find any official docs showing how to merge multiple strings into a new string.

What I'm expecting:

Input: "key:", "value", ", key2:", 100

Output: "Key:value, key2:100"

I want to use + to merge strings like in Java and Swift if possible.

Possible duplicate of [Golang: format a string without printing?](http://stackoverflow.com/questions/11123865/golang-format-a-string-without-printing) — icza, Feb 25 '16 at 00:19

score 73 · Accepted Answer · edited Jul 24 '20 at 01:21

73

I like to use fmt's Sprintf method for this type of thing. It works like Printf in Go or C only it returns a string. Here's an example:

output := fmt.Sprintf("%s%s%s%d", "key:", "value", ", key2:", 100)

Go docs for fmt.Sprintf

edited Jul 24 '20 at 01:21

Arnav Borborah

answered Feb 25 '16 at 00:19

evanmcdonnal

the last one is int number. Can I use %d ? – Yi Jiang Feb 25 '16 at 00:32
@RobertYiJiang yea, I'll edit with that in fact. Didn't realize I changed the type of the input there. – evanmcdonnal Feb 25 '16 at 00:40

score 23 · Answer 2 · answered Feb 25 '16 at 10:29

23

You can use strings.Join, which is almost 3x faster than fmt.Sprintf. However it can be less readable.

output := strings.Join([]string{"key:", "value", ", key2:", strconv.Itoa(100)}, "")

strings.Join vs fmt.Sprintf

BenchmarkFmt-4       2000000           685 ns/op
BenchmarkJoins-4     5000000           244 ns/op

Buffer

If you need to merge a lot of strings, I'd consider using a buffer rather than those solutions mentioned above.

answered Feb 25 '16 at 10:29

basgys

3

Well, if you use strconv.Itoa then you can as well concatenate strings with + – Colin Pitrat Oct 26 '17 at 15:40
1

@ColinPitrat Due to an issue on the go compiler, strings.Join of 2 or 3 elements use +, but above that it creates a byte slice for a more efficient concatenation. If you have more than two elements to concatenate, I would strongly recommend to use strings.Join. – basgys Oct 29 '17 at 21:41

Sandeep Patel · Answer 3 · 2020-04-18T18:27:58.807

2

You can simply do this:

import (
    "fmt" 
    "strconv"
)

func main() {


     result:="str1"+"str2"+strconv.Itoa(123)+"str3"+strconv.Itoa(12)
     fmt.Println(result)

}

Using fmt.Sprintf()

var s1="abc"
var s2="def"
var num =100
ans:=fmt.Sprintf("%s%d%s", s1,num,s2);
fmt.Println(ans);

edited Apr 18 '20 at 18:27

answered Apr 07 '20 at 08:20

Sandeep Patel

score 0 · Answer 4 · answered Apr 01 '21 at 19:32

0

Another option:

package main
import "fmt"

func main() {
   s := fmt.Sprint("key:", "value", ", key2:", 100)
   println(s)
}

answered Apr 01 '21 at 19:32

Steven Penny

4 Answers4