C#統計文本檔案中的行數，用3中方法對一個300k 的檔案進行統計的結果

統計文本檔案中的行數，用3中方法對一個300k 的檔案進行統計的結果：

第一次：

StreamReader.Read()：共2761行,耗時：6.08

FileStream.Read()：共2761行,耗時：11.23

StreamReader.ReadLine()：共2761行,耗時：3.61

第二次：

StreamReader.Read()：共2761行,耗時：8.87

FileStream.Read()：共2761行,耗時：14.74

StreamReader.ReadLine()：共2761行,耗時：4.14

第三次：

StreamReader.Read()：共2761行,耗時：6.39

FileStream.Read()：共2761行,耗時：14.1

StreamReader.ReadLine()：共2761行,耗時：4.76

本以為 StreamReader.ReadLine() 方法統計會很慢，結果.....。如果有快速統計算法分享下

http://blog.csdn.net/xxj_jing/article/details/52063883

測試代碼如下：

using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;

namespace TestGrass.Log
{
    [TestClass]
    public class TestTxtRead
    {
        public string _minFile = @"D:\temp\logs\***.txt";
        public string _maxFile = @"D:\temp\logs\***.log";
        /// <summary>
        /// 回車符 \n=13=0x0D
        /// </summary>
        public byte _enter = 0x0D;
        /// <summary>
        /// 換行符 \r=10=0x0A
        /// </summary>
        public byte _return = 0x0A;
        [TestMethod]
        public void TestStream()
        {
            /*
             * 讀取300k檔案耗時
             * StreamReader.Read() 用時 8.19s
             * FileStream.Read() 用時
             * StreamReader.ReadLine() 用時 2.83s
             */
            byte n = 0xD;
            byte r = 0xA;
            StringBuilder msg = new StringBuilder();
            Stopwatch sw = new Stopwatch();
            var path = _minFile;
            int lines1 = 0;
            int lines2 = 0;
            int lines3 = 0;
            //單個字元讀取
            sw.Start();
            using (var sr = new StreamReader(path))
            {
                int val = 0;
                val = sr.Read();
                //while ((val=sr.Read()) != -1)
                while(val!=-1)
                {
                    if (val == n)
                        lines1++;
                    val = sr.Read();
                }
            }
            sw.Stop();
            msg.AppendLine(string.Format("StreamReader.Read()：共{0}行,耗時：{1}"
                ,lines1
                ,Math.Round(sw.ElapsedTicks*1.0/1000,2)));


            //使用緩沖讀取
            Action<byte[]> totalizer = (arr)=>
            {
                lines2 += arr.Count(x => { return x == n; });
            };
            sw.Restart();
            
            using (var fs = new FileStream(path,FileMode.Open))
            {
                var buffer = new byte[1024];
                var rc = fs.Read(buffer, 0, buffer.Length);
                totalizer(buffer);
                
                while (rc!=0)
                {
                    buffer = new byte[1024];
                    rc = fs.Read(buffer, 0, buffer.Length);
                    totalizer(buffer);
                }
            }
            sw.Stop();
            msg.AppendLine(string.Format("FileStream.Read()：共{0}行,耗時：{1}"
                , lines2
                , Math.Round(sw.ElapsedTicks * 1.0 / 1000, 2)));

            //按行讀取
            sw.Restart();
            using (var sr = new StreamReader(path))
            {
                var ls = "";
                while ((ls=sr.ReadLine()) != null)
                {
                    lines3++;
                }
            }
            sw.Stop();
            msg.AppendLine(string.Format("StreamReader.ReadLine()：共{0}行,耗時：{1}"
                , lines3
                , Math.Round(sw.ElapsedTicks * 1.0 / 1000, 2)));
            string str = msg.ToString();
            Assert.IsTrue(true);
        }
    }

}