C＃创建如何创建具有日期格式的唯一字符串 [英] C# Create how do I create a unique string with date format

问题描述

为什么myDate在循环中保持值？

即使下降到微秒，字符串在每次运行时应该有不同的值。

我无法想象处理器很快。我甚至尝试使用Thread.Sleep强制它在循环中等待。我对C＃相当新，也许我错过了一些明显的东西。

Why does myDate hold the value in the loop?
Even going down to microsecond the string should have a different value on each run.
I can't imagine the processor is that fast. I even attempted putting Thread.Sleep to force it to wait in the loop. I am fairly new to C# maybe I am missing something obvious.

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {

            string myDate;

            for (int i = 0; i <= 100000; i++)
            {
                myDate = String.Empty;
                myDate = DateTime.Now.ToString("hh:mm:ss:fff:ms");
                Console.WriteLine(myDate);
            }
            Console.ReadLine();
        }
    }
}

推荐答案

您的计算机处理器非常快。使用日期时间字段几乎不可能完成唯一标识符。



您应该使用全局唯一标识符来获得所需的结果。





推荐阅读：



http://en.wikipedia.org/wiki/Globally_unique_identifier < br $>
http://msdn.microsoft.com/en-us/library/system.guid.aspx





JAFC

Your computer processor is really fast. It is almost impossible to accomplish a unique identifier using a datetime field.

You should use a globally unique identifier to obtain the desired result.


Recommend reading:

http://en.wikipedia.org/wiki/Globally_unique_identifier
http://msdn.microsoft.com/en-us/library/system.guid.aspx


JAFC

你的电脑真的那么快，这就是为什么你并不总是有不同的价值。您可以使用 System.Diagnostics 命名空间中的秒表类来查找运行循环所需的时间：

Your computer is really that fast, and that's why you don't always have a different value. You can use the Stopwatch class in the System.Diagnostics namespace to find out how long it takes to run your loop:

string myDate;

System.Diagnostics.Stopwatch sw = new System.Diagnostics.Stopwatch();
sw.Start();
for (int i = 0; i <= 100000; i++)
{
    myDate = String.Empty;
    myDate = DateTime.Now.ToString("hh:mm:ss:fff:ms");
    Console.WriteLine(myDate);
}
sw.Stop();
Console.WriteLine(sw.Elapsed.ToString());

Console.ReadLine();

我得到这个结果：

And I get this result:

00:00:05.1339143

因此，运行循环（在我的计算机上）只需要五秒钟。所以，如果你真的总想得到不同的结果，那么你应该使用 Thread.Sleep 。

添加Thread.Sleep（10）允许足够的时间让毫秒改变。它应该足够独特，我需要的东西。我并不担心这个循环的总时间。它不被用于任何关键的东西。而不是平面文件上的唯一键。

我认为我的问题是我之前在代码的错误部分有睡眠。

Adding Thread.Sleep(10) allows enough time for the milliseconds to change. it should be unique enough for what I need. I am not worried about the overall time of this loop. It isn't being used for anything critical. Rather than a unique key on a flat file.
I think my issue was I had the Sleep in the wrong part of the code before.

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {

            string myDate;

            for (int i = 0; i <= 100; i++)
            {
                myDate = String.Empty;
                myDate = DateTime.Now.ToString("hh:mm:ss:fff");
                Console.WriteLine(myDate);
                Thread.Sleep(10);

            }
            Console.ReadLine();
        }
    }
}

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