对于那些晚到这个话题的人来说，我可以看到hitscan的“你可能不应该这样做”可能会让一些人问他们应该怎么做……

StringBuilder类通常是一个简单的替代。 如果您的数据来自一个文件，请特别考虑一个基于流的类。

s += "stuff"的问题是，它必须分配一个全新的区域来保存数据，然后将所有旧数据复制到它加上新数据-每一次循环迭代。因此，用s += "stuff"在1,000,000中增加5个字节的开销非常大。 如果你想只写5个字节到最后，然后继续你的程序，你必须选择一个留出一些增长空间的类:

StringBuilder sb = new StringBuilder(5000);
for (; ; )
    {
        sb.Append("stuff");
    }

当StringBuilder达到限制时，它会自动增长一倍。所以，你会在开始时看到增长的痛苦，一次是5000字节，一次是10000字节，一次是20000字节。追加字符串将在每次循环迭代中引起痛苦。

根据我高度科学和精确的实验，它在我的机器上达到了10亿个字符。(我仍在运行下面的代码以获得更好的精确位置)。

更新: 几个小时后，我放弃了。最终结果:能够在系统中创造出超过1亿个字符的内容。OutOfMemoryException在1,000,000,000个字符。

using System;
using System.Collections.Generic;

public class MyClass
{
    public static void Main()
    {
        int i = 100000000;
        try
        {
            for (i = i; i <= int.MaxValue; i += 5000)
            {
                string value = new string('x', i);
                //WL(i);
            }
        }
        catch (Exception exc)
        {
            WL(i);
            WL(exc);
        }
        WL(i);
        RL();
    }

    #region Helper methods

    private static void WL(object text, params object[] args)
    {
        Console.WriteLine(text.ToString(), args);   
    }

    private static void RL()
    {
        Console.ReadLine(); 
    }

    private static void Break() 
    {
        System.Diagnostics.Debugger.Break();
    }

    #endregion
}

因为字符串。Length是一个整数(这是Int32的别名)，其大小限制为Int32。MaxValue unicode字符。: -)

在我的机器上，字符串的最大长度是1,073,741,791。

你看，字符串并不像通常认为的那样受整数限制。

除了内存限制外，字符串不能超过230(1,073,741,824)个字符，因为Microsoft CLR(公共语言运行时)施加了2GB的限制。比我电脑允许的多33个。

现在，这里有一些东西欢迎你自己尝试。

在Visual Studio中创建一个新的c#控制台应用程序，然后复制/粘贴main方法:

static void Main(string[] args)
{
    Console.WriteLine("String test, by Nicholas John Joseph Taylor");

    Console.WriteLine("\nTheoretically, C# should support a string of int.MaxValue, but we run out of memory before then.");

    Console.WriteLine("\nThis is a quickish test to narrow down results to find the max supported length of a string.");

    Console.WriteLine("\nThe test starts ...now:\n");

    int Length = 0;

    string s = "";

    int Increment = 1000000000; // We know that s string with the length of 1000000000 causes an out of memory exception.

    LoopPoint:

    // Make a string appendage the length of the value of Increment

    StringBuilder StringAppendage = new StringBuilder();

    for (int CharacterPosition = 0; CharacterPosition < Increment; CharacterPosition++)
    {
        StringAppendage.Append("0");

    }

    // Repeatedly append string appendage until an out of memory exception is thrown.

    try
    {
        if (Increment > 0)
            while (Length < int.MaxValue)
            {
                Length += Increment;

                s += StringAppendage.ToString(); // Append string appendage the length of the value of Increment

                Console.WriteLine("s.Length = " + s.Length + " at " + DateTime.Now.ToString("dd/MM/yyyy HH:mm"));

            }

    }
    catch (OutOfMemoryException ex) // Note: Any other exception will crash the program.
    {
        Console.WriteLine("\n" + ex.Message + " at " + DateTime.Now.ToString("dd/MM/yyyy HH:mm") + ".");

        Length -= Increment;

        Increment /= 10;

        Console.WriteLine("After decimation, the value of Increment is " + Increment + ".");

    }
    catch (Exception ex2)
    {
        Console.WriteLine("\n" + ex2.Message + " at " + DateTime.Now.ToString("dd/MM/yyyy HH:mm") + ".");

        Console.WriteLine("Press a key to continue...");

        Console.ReadKey();

    }

    if (Increment > 0)
    {
        goto LoopPoint;

    }

    Console.WriteLine("Test complete.");

    Console.WriteLine("\nThe max length of a string is " + s.Length + ".");

    Console.WriteLine("\nPress any key to continue.");

    Console.ReadKey();

}

我的研究结果如下:

String test, by Nicholas John Joseph Taylor Theoretically, C# should support a string of int.MaxValue, but we run out of memory before then. This is a quickish test to narrow down results to find the max supported length of a string. The test starts ...now: s.Length = 1000000000 at 08/05/2019 12:06 Exception of type 'System.OutOfMemoryException' was thrown. at 08/05/2019 12:06. After decimation, the value of Increment is 100000000. Exception of type 'System.OutOfMemoryException' was thrown. at 08/05/2019 12:06. After decimation, the value of Increment is 10000000. s.Length = 1010000000 at 08/05/2019 12:06 s.Length = 1020000000 at 08/05/2019 12:06 s.Length = 1030000000 at 08/05/2019 12:06 s.Length = 1040000000 at 08/05/2019 12:06 s.Length = 1050000000 at 08/05/2019 12:06 s.Length = 1060000000 at 08/05/2019 12:06 s.Length = 1070000000 at 08/05/2019 12:06 Exception of type 'System.OutOfMemoryException' was thrown. at 08/05/2019 12:06. After decimation, the value of Increment is 1000000. s.Length = 1071000000 at 08/05/2019 12:06 s.Length = 1072000000 at 08/05/2019 12:06 s.Length = 1073000000 at 08/05/2019 12:06 Exception of type 'System.OutOfMemoryException' was thrown. at 08/05/2019 12:06. After decimation, the value of Increment is 100000. s.Length = 1073100000 at 08/05/2019 12:06 s.Length = 1073200000 at 08/05/2019 12:06 s.Length = 1073300000 at 08/05/2019 12:06 s.Length = 1073400000 at 08/05/2019 12:06 s.Length = 1073500000 at 08/05/2019 12:06 s.Length = 1073600000 at 08/05/2019 12:06 s.Length = 1073700000 at 08/05/2019 12:06 Exception of type 'System.OutOfMemoryException' was thrown. at 08/05/2019 12:06. After decimation, the value of Increment is 10000. s.Length = 1073710000 at 08/05/2019 12:06 s.Length = 1073720000 at 08/05/2019 12:06 s.Length = 1073730000 at 08/05/2019 12:06 s.Length = 1073740000 at 08/05/2019 12:06 Exception of type 'System.OutOfMemoryException' was thrown. at 08/05/2019 12:06. After decimation, the value of Increment is 1000. s.Length = 1073741000 at 08/05/2019 12:06 Exception of type 'System.OutOfMemoryException' was thrown. at 08/05/2019 12:06. After decimation, the value of Increment is 100. s.Length = 1073741100 at 08/05/2019 12:06 s.Length = 1073741200 at 08/05/2019 12:06 s.Length = 1073741300 at 08/05/2019 12:07 s.Length = 1073741400 at 08/05/2019 12:07 s.Length = 1073741500 at 08/05/2019 12:07 s.Length = 1073741600 at 08/05/2019 12:07 s.Length = 1073741700 at 08/05/2019 12:07 Exception of type 'System.OutOfMemoryException' was thrown. at 08/05/2019 12:07. After decimation, the value of Increment is 10. s.Length = 1073741710 at 08/05/2019 12:07 s.Length = 1073741720 at 08/05/2019 12:07 s.Length = 1073741730 at 08/05/2019 12:07 s.Length = 1073741740 at 08/05/2019 12:07 s.Length = 1073741750 at 08/05/2019 12:07 s.Length = 1073741760 at 08/05/2019 12:07 s.Length = 1073741770 at 08/05/2019 12:07 s.Length = 1073741780 at 08/05/2019 12:07 s.Length = 1073741790 at 08/05/2019 12:07 Exception of type 'System.OutOfMemoryException' was thrown. at 08/05/2019 12:07. After decimation, the value of Increment is 1. s.Length = 1073741791 at 08/05/2019 12:07 Exception of type 'System.OutOfMemoryException' was thrown. at 08/05/2019 12:07. After decimation, the value of Increment is 0. Test complete. The max length of a string is 1073741791. Press any key to continue.

我的机器上字符串的最大长度是1073741791。

如果大家能在下面留言，我会非常感激的。

如果人们得到相同或不同的结果，这将是很有趣的。

String在RAM的堆中分配动态内存大小。但是字符串地址存储在堆栈中，占用4个字节的内存。

由于系统的长度属性。字符串是Int32，我猜最大长度将是2147,483,647个字符(最大Int32大小)。如果它允许更长的时间，你就不能检查长度，因为那会失败。