package main
import (
"regexp"
"fmt"
)
func main() {
var re = regexp.MustCompile(`(?m)^(?:(?:(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])\.){3}(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])(?:-(?:(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])\.){3}(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])|\/(?:[0-9]|[1-2][0-9]|3[0-2]))?|(?:[a-z0-9]+(?:-[a-z0-9]+)*\.)+[a-z]{2,})$`)
var str = `Valid
1.2.3.4
255.255.255.255
1.2.3.4-1.2.3.4
1.2.3.4/24
1.2.3.4/8
www.example.com
www.example.lv
www.example.com
Invalid
1.2.3
1.2.3.
.1.2.3
1.2.3.4/33
www.-example.com
1.2.3.4-1.2.3.256
1.2.3.4.5.6.7.8 (use anchors ^ and $ to skip these if needed)
999.999.999.999 (use a complex regex to skip these if needed)
299.299.299.299
001.002.003.004 (these use octal notation, not decimal)
`
for i, match := range re.FindAllString(str, -1) {
fmt.Println(match, "found at index", i)
}
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Golang, please visit: https://golang.org/pkg/regexp/