using System.Text.RegularExpressions;
public static void Main()
"^[\\u0041-\\u005A\\u0061-\\u007A]*$",
"^[\\u0041-\\u005A\\u0061-\\u007A\\u0030-\\u0039]*$",
string[] inputs = { "0493", "JAKE", "jake", "Jake", "J4k3", "Jæke" };
foreach (string pattern in patterns)
Console.WriteLine(pattern);
var re = new Regex(pattern);
foreach (string input in inputs)
var match = re.IsMatch(input);
var icon = match ? '✅' : '❌';
Console.Write($"{icon} {input}\t");