Console.ReadLine() max length?

Question

When running a small piece of C# code, when I try to input a long string into Console.ReadLine() it seems to cut off after a couple of lines.

Is there a max length to Console.Readline(), if so is there a way to increase that?

Answer 1

An issue with stack72's answer is that if the code is used in a batch-script the input is no longer line buffered. I found an alternative version at averagecoder.net that keeps the ReadLine call. Note that StreamReader also must have a length argument, since it has a fixed buffer as well.

byte[] inputBuffer = new byte[1024]; 
Stream inputStream = Console.OpenStandardInput(inputBuffer.Length);
Console.SetIn(new StreamReader(inputStream, Console.InputEncoding, false, inputBuffer.Length));
string strInput = Console.ReadLine();

Answer 2

Without any modifications to the code it will only take a maximum of 256 characters ie; It will allow 254 to be entered and will reserve 2 for CR and LF.

The following method will help to increase the limit:

private static string ReadLine()
    {
        Stream inputStream = Console.OpenStandardInput(READLINE_BUFFER_SIZE);
        byte[] bytes = new byte[READLINE_BUFFER_SIZE];
        int outputLength = inputStream.Read(bytes, 0, READLINE_BUFFER_SIZE);
        //Console.WriteLine(outputLength);
        char[] chars = Encoding.UTF7.GetChars(bytes, 0, outputLength);
        return new string(chars);
    }

Answer 3

This is a simplified version of ara's answer and it works for me.

int bufSize = 1024;
Stream inStream = Console.OpenStandardInput(bufSize);
Console.SetIn(new StreamReader(inStream, Console.InputEncoding, false, bufSize));

string line = Console.ReadLine();

Answer 4

This is a simplified version of Petr Matas' answer. Basically you can specify the buffer size only once as follow :

Console.SetIn(new StreamReader(Console.OpenStandardInput(),
                               Console.InputEncoding,
                               false,
                               bufferSize: 1024));
string line = Console.ReadLine();

Because in the end

Console.OpenStandardInput(int bufferSize)

calls

private static Stream GetStandardFile(int stdHandleName, FileAccess access, int bufferSize)

which doesn't use bufferSize !

Answer 5

Console.ReadLine() has a 254 character limit.

I found the below single line of code here. That seemed to do the trick.

Console.SetIn(new StreamReader(Console.OpenStandardInput(8192)));

Answer 6

ReadLine() internally reads character by character until a -1 or '\n' or '\r\n' is encountered.

    public virtual String ReadLine()
    { 
        StringBuilder sb = new StringBuilder();
        while (true) { 
            int ch = Read(); 
            if (ch == -1) break;
            if (ch == '\r' || ch == '\n') 
            {
                if (ch == '\r' && Peek() == '\n') Read();
                return sb.ToString();
            } 
            sb.Append((char)ch);
        } 
        if (sb.Length > 0) return sb.ToString(); 
        return null;
    } 

Answer 7

If it is a matter of seeing the entire output of the text in the Console, I have found that the following code works to display it:

Console.SetBufferSize(128, 1024);

Answer 8

This appears to be a limitation of the Windows console. You should try putting your input into a file, and then piping the file into the application. I am not certain if that will work, but it has a chance.

regex_text.exe < my_test_data.txt

Answer 9

Depending on your OS, the command line input will only accept 8191 characters for XP and 2047 characters for NT and Windows 2000. I suggest you pass a filename instead which has your long input and read that file.

Answer 10

Save the input into text and use StreamReader.

using System;

using System.IO;

static void Main(string[] args)
{

    try
    {
        StreamReader sr = new StreamReader("C:\\Test\\temp.txt");
        Console.WriteLine(sr.ReadLine().Length);
    }
    catch (Exception e)
    {
         Console.WriteLine(e.StackTrace);
    }
}