C# 判断字符串第一位是否为数字

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Text.RegularExpressions;

namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
Regex regChina = new Regex( "^[^/x00-/xFF]");
Regex regNum = new Regex( "^[0-9]");
Regex regChar = new Regex( "^[a-z]");
Regex regDChar = new Regex( "^[A-Z]");
string str = "YL闫磊";
if (regNum.IsMatch(str))
{
MessageBox.Show( "是数字");
}
else if (regChina.IsMatch(str))
{
MessageBox.Show( "是中文");
}
else if (regChar.IsMatch(str))
{
MessageBox.Show( "小写");
}
else if (regDChar.IsMatch(str))
{
MessageBox.Show( "大写");
}
}
}
}