What is the maximum possible length of a .NET string?

McKenzieG1_3776 0
Viewed 388691

What is the longest string that can be created in .NET? The docs for the String class are silent on this question as far as I can see, so an authoritative answer might require some knowledge of internals. Would the maximum change on a 64-bit system?

[This is asked more for curiosity than for practical use - I don't intend to create any code that uses gigantic strings!]

limits string .net
8 Answers

The theoretical limit may be 2,147,483,647, but the practical limit is nowhere near that. Since no single object in a .NET program may be over 2GB and the string type uses UTF-16 (2 bytes for each character), the best you could do is 1,073,741,823, but you're not likely to ever be able to allocate that on a 32-bit machine.

This is one of those situations where "If you have to ask, you're probably doing something wrong."

HitScan_94900

Based on my highly scientific and accurate experiment, it tops out on my machine well before 1,000,000,000 characters. (I'm still running the code below to get a better pinpoint).

UPDATE: After a few hours, I've given up. Final results: Can go a lot bigger than 100,000,000 characters, instantly given System.OutOfMemoryException at 1,000,000,000 characters.

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
}
bdukes_26880

Since the Length property of System.String is an Int32, I would guess that that the maximum length would be 2,147,483,647 chars (max Int32 size). If it allowed longer you couldn't check the Length since that would fail.

Ryan_Farley_16270

Since String.Length is an integer (that is an alias for Int32), its size is limited to Int32.MaxValue unicode characters. ;-)

David_Humpohl_210380

200 megs... at which point your app grinds to a virtual halt, has about a gig working set memory, and the o/s starts to act like you'll need to reboot.

static void Main(string[] args)
{
    string s = "hello world";
    for(;;)
    {
        s = s + s.Substring(0, s.Length/10);
        Console.WriteLine(s.Length);
    }
}

12
13
14
15
16
17
18
...
158905664
174796230
192275853
211503438
loudej_60560

String allocates dynamic memory size in the heap of your RAM. But string address is stored in stack that occupies 4 bytes of memory.

user_144405730
Related