C# 写CSV文件字符串前面0不显示的解决办法

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CsvTest
{
    class Program
    {
        static void Main(string[] args)
        {
            FileStream fs = File.OpenWrite("D:\\test.csv");
            StreamWriter sw = new StreamWriter(fs);
            sw.WriteLine(((char)(9)).ToString()  +"012345");
            sw.Close();
        }
    }
}