C#：如何检查这些字符串是否只包含数字和字母？(Regex)

using System;
using System.Text.RegularExpressions;

class Program
{
    static void Main()
    {
        string input = "Abc123";
        bool isAlphaNumeric = IsAlphaNumeric(input);
        Console.WriteLine(isAlphaNumeric);
    }

    static bool IsAlphaNumeric(string input)
    {
        Regex regex = new Regex("^[a-zA-Z0-9]+$");
        return regex.IsMatch(input);
    }
}