Golang : Generate random string

In this tutorial, we will learn how to generate random string in Golang. Random strings can be used in many applications, such as generating random identifiers for job code, session id, secure token and many others.

 package main

 import (
 "encoding/base64"
 "crypto/rand"
 "fmt"
 )

 func main() {
 size := 32 // change the length of the generated random string here

 rb := make([]byte,size)
 _, err := rand.Read(rb)


 if err != nil {
 fmt.Println(err)
 }

 rs := base64.URLEncoding.EncodeToString(rb)

 fmt.Println(rs)
 }

Output :

>go run randomstr.go

k38b1e3c4YVQJ4FMrgcRBLU2DyEuDlyxVNjy3UA7sIw=

>go run randomstr.go

b6NW5LJY1gI5Hui7oWZbTJa_LCsL__JaJ33zZ5NIXHE=

In real world application, the above random string generation codes will be good for any practical use. The reason I put it there is to show you one way of generating random string.

It would be a good idea to write a function for generating random string(that is able to handle alphanumerica, alpha or numeric) and put the function in a package for easier calling. See randStr() function below :

 package main

 import (
 "crypto/rand"
 "fmt"
 )

 func randStr(strSize int, randType string) string {

 var dictionary string

 if randType == "alphanum" {
 dictionary = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
 }

 if randType == "alpha" {
 dictionary = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
 }

 if randType == "number" {
 dictionary = "0123456789"
 }

 var bytes = make([]byte, strSize)
 rand.Read(bytes)
 for k, v := range bytes {
 bytes[k] = dictionary[v%byte(len(dictionary))]
 }
 return string(bytes)
 }

 func main() {

 fmt.Println("Alphanum : ", randStr(16, "alphanum"))

 fmt.Println("Alpha : ", randStr(16, "alpha"))

 fmt.Println("Numbers : ", randStr(16, "number"))

 }

Output (sample) :

Alphanum : jem7veyr7VVi2gNT

Alpha : UYqbhKPACfHsvjLh

Numbers : 8892932200439488

Hope this tutorial can be useful to you.