Golang : Regular Expression for alphanumeric and underscore

Problem :

Need a regular expression that only allows upper, lowercase characters, underscores and numbers for Go.

Solution :

Use this regular expression

"^[a-zA-Z0-9_]*$"

Explanations:

^ : start of string

[ : beginning of character group

a-z : any lowercase letter

A-Z : any uppercase letter

0-9 : any digit

_ : underscore

] : end of character group

* : zero or more of the given characters

$ : end of string

Go source code :

 package main

 import "fmt"
 import "regexp"

 func main() {

  a := "testing_123"

  re := regexp.MustCompile("^[a-zA-Z0-9_]*$")
  fmt.Println(re.MatchString("123"))
  fmt.Println(re.MatchString("abc"))
  fmt.Println(re.MatchString(a))
  fmt.Println(re.MatchString("世界"))

 }

Output :

true

true

true

false

Reference :

http://stackoverflow.com/questions/336210/regular-expression-for-alphanumeric-and-underscores