using System;

public class Validate

{

    public static bool IsNumericDigit(char c) {

    return '0' <= c && c <= '9';

  }

​

  public static bool HasNumericDigits(string s) {

    for (int i = 0; i < s.Length; i++) {

      if (IsNumericDigit(s[i])) return true;

    }

    return false;

  }

​

  public static bool IsValidPhoneNumber(string s, out string strPhoneNumber) {

    strPhoneNumber = "";

    for (int i=0; i < s.Length; i++) {

      if (IsNumericDigit(s[i]))

        strPhoneNumber += s[i];

      else switch (s[i]) {

        case '-' :

        case '.' :

        case ' ' :

        case '(' :

        case ')' : 

          break;

        default:

          return false; 

      }

    }

    return strPhoneNumber.Length == 10;

  }

​

  public static bool IsValidEmail(string s) {

        string[] word;

        // Check the presence of exactly one @ character and non-empty user name

        word = s.Split('@');

        if (word.Length != 2 || word[0].Length == 0)

            return false;

​

        // Check the presence of exactly one dot character and non-empty domain name

        string domain = word[1];

        word = domain.Split('.');

        if (word.Length != 2 || word[0].Length == 0)

            return false;

​

        // Check the domain suffix

    string suffix = word[1];

        switch (suffix) {

            case "com":

            case "net":

            case "org":

            case "me":

                break;

            default:

                return false;

        }

        return true;

    }

}