package main
import (
"regexp"
"fmt"
)
func main() {
var re = regexp.MustCompile(`(?m)(^[A-Za-z][A-Za-z0-9\.\-\_]+$)|(^[\w\-\.\+]+@([\w-]+\.)+[\w-]{2,4}$)`)
var str = `User1.2.3
simpleuser123
simpleuser_123
simpleuser-123
1baduser
.baduser
_baduser
1bob-is.great_999+456@gmail.com`
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/