Windows File Path

const re = new RegExp("^[A-Za-z]:\\\\(?:[^\\\\/:*?\"<>|\\r\\n]+\\\\)*[^\\\\/:*?\"<>|\\r\\n]*$", "");
const input = "C:\\Users\\John\\file.txt";
const match = input.match(re);
console.log(match ? match[0] : null);

import re

pattern = re.compile(r"^[A-Za-z]:\\\\(?:[^\\\\/:*?\"<>|\\r\\n]+\\\\)*[^\\\\/:*?\"<>|\\r\\n]*$")
input_text = "C:\Users\John\file.txt"
for m in pattern.finditer(input_text):
    print(m.group(0))

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`^[A-Za-z]:\\(?:[^\\/:*?"<>|\r\n]+\\)*[^\\/:*?"<>|\r\n]*$`)
	input := `C:\Users\John\file.txt`
	for _, match := range re.FindAllString(input, -1) {
		fmt.Println(match)
	}
}