How to open a large text file in C#

Question

I have a text file that contains about 100000 articles. The structure of file is:

.Document ID 42944-YEAR:5
.Date  03\08\11
.Cat  political
Article Content 1

.Document ID 42945-YEAR:5
.Date  03\08\11
.Cat  political
Article Content 2

I want to open this file in c# for processing it line by line. I tried this code:

String[] FileLines = File.ReadAllText(
                  TB_SourceFile.Text).Split(Environment.NewLine.ToCharArray()); 

But it says:

Exception of type 'System.OutOfMemoryException' was thrown.

The question is How can I open this file and read it line by line.

• File Size: 564 MB (591,886,626 bytes)
• File Encoding: UTF-8
• File contains Unicode characters.

Answer 1

You can open the file and read it as a stream rather than loading everything into memory all at once.

From MSDN:

using System;
using System.IO;

class Test 
{
    public static void Main() 
    {
        try 
        {
            // Create an instance of StreamReader to read from a file.
            // The using statement also closes the StreamReader.
            using (StreamReader sr = new StreamReader("TestFile.txt")) 
            {
                String line;
                // Read and display lines from the file until the end of 
                // the file is reached.
                while ((line = sr.ReadLine()) != null) 
                {
                    Console.WriteLine(line);
                }
            }
        }
        catch (Exception e) 
        {
            // Let the user know what went wrong.
            Console.WriteLine("The file could not be read:");
            Console.WriteLine(e.Message);
        }
    }
}