请大家帮忙优化下代码!
以前一直是做WEB开发,ASP.NET,最近公司要求做一个能生成5万条互不相同的字符串的功能.
用VS2005创建windows程序,windows程序写好后测试能生成5万条.但是效率很低,花了3分钟时间,CPU使用率在98%-100%之间徘徊.
我的代码如下,想请各位帮忙给优化下,让代码跑起来快些.(初次写windows程序,有很多不懂,希望在CSDN请教各位达人!)
Form1.cs代码:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Text;

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

private void button1_Click(object sender, EventArgs e)
{
string code = "";
for (int i = 1; i <= 50000; i++)
{
code += rc(i) + "\r\n";
}
label1.Text="已生成五万条随机字符串";
string path = "D:/";
Encoding codee = Encoding.GetEncoding("UTF-8");
StreamWriter sw = new StreamWriter(path + "string.txt", false, codee);
sw.Write(code);
sw.Flush();
sw.Close();
label1.Text = "生成文件成功,文件名为:string.txt";
}

public static string rc(int a)
{
char[] arrchar = new char[]{
'0','1','2','3','4','5','6','7','8','9',
'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'
};
StringBuilder num = new StringBuilder();
Random rnd = new Random(a);
for (int i = 1; i <= 4; i++)
{
//num2.Append(arrchar[rnd.Next(0,10)].ToString());
//num.Append(arrchar[rnd.Next(0, 10)].ToString());
num.Append(arrchar[rnd.Next(11, arrchar.Length)].ToString());
}
for (int j = 1; j <= 8; j++)
{
num.Append(arrchar[rnd.Next(0, 10)].ToString());
}


return num.ToString();
}
}
}

[解决办法]
在我机器上耗时125毫秒

C# code

private const int CODE_COUNT = 50000; // 记录数private byte[] codeBuffer = new byte[14 * CODE_COUNT];private Random random = new Random(); public byte[] RandomCode(){    byte[] vReturn = new byte[14];    vReturn[12] = 13;    vReturn[13] = 10;    for (int i = 0; i < 4; i++)        vReturn[i] = (byte)('A' + random.Next(26));    for (int i = 4; i < 12; i++)        vReturn[i] = (byte)('0' + random.Next(10));    return vReturn;}private Hashtable vHashtable = new Hashtable();private void button1_Click(object sender, EventArgs e){    long vTickCount = Environment.TickCount;    byte[] code = RandomCode();    for (int i = 0; i < CODE_COUNT; )    {        code = RandomCode();        if (!vHashtable.Contains(code)) // 避免重复        {            vHashtable.Add(code, null);            Array.Copy(code, 0, codeBuffer, i * 14, code.Length);            i++;        }    }    FileStream vFileStream = new FileStream(@"c:\temp\temp.txt",         FileMode.Create, FileAccess.Write);    int vPos = 0;    for (; vPos + 0x1000 < codeBuffer.Length; vPos += 0x1000)    {        vFileStream.Write(codeBuffer, vPos, 0x1000); // 减少文件写入的次数，采用每4096字节写一次。    }    vFileStream.Write(codeBuffer, vPos, codeBuffer.Length - vPos);    vFileStream.Close();    Console.WriteLine("耗时：{0}毫秒", Environment.TickCount - vTickCount);} 
 
[解决办法]
在zswang代码的基础上，稍微修改了一下:
C# code
using System;using System.Collections.Generic;using System.IO;using System.Diagnostics;namespace ConsoleApplication5{    class Program    {        private const int CODE_COUNT = 50000; // 记录数        private static readonly byte[] NewLine ={ 13, 10 };        private static Random random = new Random();        static void Main(string[] args)        {            Console.Write("Press Enter to start:");            Console.ReadLine();            Stopwatch sw = Stopwatch.StartNew();            using (FileStream fs = new FileStream("test.txt", FileMode.Create, FileAccess.Write))            using (BinaryWriter bw = new BinaryWriter(fs))                Exec(bw);            sw.Stop();            Console.WriteLine("耗时：{0}毫秒", sw.ElapsedMilliseconds);            Console.ReadLine();        }        public static void RandomCode(ref byte[] buffer)        {            for (int i = 0; i < 4; i++)                buffer[i] = (byte)('A' + random.Next(26));            for (int i = 4; i < 12; i++)                buffer[i] = (byte)('0' + random.Next(10));        }        private static void Exec(BinaryWriter bw)        {            Dictionary<int, int> codes = new Dictionary<int, int>(CODE_COUNT);            byte[] buffer = new byte[12];            int count = 0;            while (count < CODE_COUNT)            {                RandomCode(ref buffer);                int hash = Hash(buffer);                if (!codes.ContainsKey(hash))                {                    codes.Add(hash, 0);                    bw.Write(buffer);                    bw.Write(NewLine);                    count++;                }            }        }        private static int Hash(byte[] buffer)        {            return BitConverter.ToInt32(buffer, 0) ^                BitConverter.ToInt32(buffer, 4) ^                BitConverter.ToInt32(buffer, 8);        }    }}
[解决办法]
C# code
using System.Collections;private const int CODE_COUNT = 50000; // 记录数private Random random = new Random(); public byte[] RandomCode(){    byte[] vReturn = new byte[14];    vReturn[12] = 13;    vReturn[13] = 10;    for (int i = 0; i < 4; i++)        vReturn[i] = (byte)('A' + random.Next(26));    for (int i = 4; i < 12; i++)        vReturn[i] = (byte)('0' + random.Next(10));    return vReturn;}private Dictionary<string, int> codeList = new Dictionary<string, int>();private void button1_Click(object sender, EventArgs e){    long vTickCount = Environment.TickCount;    codeList.Clear();     byte[] vCode;    FileStream vFileStream = new FileStream(@"c:\temp\temp.txt",FileMode.Create, FileAccess.Write);    for (int i = 0; i < CODE_COUNT; )    {        vCode = RandomCode();        string S = BitConverter.ToString(vCode);        if (!codeList.ContainsKey(S)) // 避免重复        {            codeList.Add(S, i);i++;            vFileStream.Write(codeBuffer, 0, codeBuffer.Length); //这样更快,因为本身有循环        }    }    vFileStream.Close();    Console.WriteLine("耗时：{0}毫秒", Environment.TickCount - vTickCount);}