golang regex ip v4 & ip v6

main.go

package main

import(
  "fmt"
  "regexp"
)

const (
  regexIPv4 = `(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})`
  regexIPv6 = `((?:[0-9A-Fa-f]{1,4}))((?::[0-9A-Fa-f]{1,4}))*::((?:[0-9A-Fa-f]{1,4}))((?::[0-9A-Fa-f]{1,4}))*|((?:[0-9A-Fa-f]{1,4}))((?::[0-9A-Fa-f]{1,4})){7}`
)

var str string = `this is a sample text with given 192.168.0.1 as an ip`

func main() {
  re := regexp.MustCompile(regexIPv4)
  // getting first match
  // to get all matches use FindAllString(source, n)
  ip := re.FindString(str)
  fmt.Println(ip)
}