package main
import (
"regexp"
"fmt"
)
func main() {
var re = regexp.MustCompile(`(?:\s|^) # Start of string or word boundary
( # Capture Group
(?: # Non-Capture Group for X.
(?: # Nested NCG for 0..255
(?:\d){1,2}| # Allow any single digit or any pair of digits or
(?:1\d{2})| # 3 Digits starting with 1 or
(?:2[0-4]\d)| # 3 Digists starting with 20..24 or
(?:25[0-5]) # 250..255
) # this should allow X=0..255 in the NCG
\. # Must be followed by a literal .
){3} # X. Must repeat exactly 3 times
(?: # NCG for final 0..255
(?:\d{1,2})| # Allow any single digit or any pair of digits or
(?:1\d{2})| # 3 Digits starting with 1 or
(?:2[0-4]\d)| # 3 digits starting 20..24 or
(?:25[0-5]) # 250.255
) # End of final 0.255
) # End of capture group
(?:\s|$) # Must be followed by EOS or wspace`)
var str = `123.123.123.145 is an IP4 so is 1.2.3.4 and 1.22.33.44 but 256.1.2.3 isn't 254.1.2.3 is but 260.1.1.1 isn't nor 2.5.256.1 and 1.2.3.4:222 IP6 1.2.3.4.5.6`
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/