Read large files in C#

The System.IO namespace exposes a couple of classes that you can use. In one of my projects I use the StreamReader and read each line of the file because it is a fixed width file that needs to be converted into an object. 

ex:

using (StreamReader streamReader = new StreamReader(FilePath))

{

   while (m_streamReader.Peek() > 0)

   {

   }

}

For files over 500mb this works fine. You can also use the StringReader or BinaryReader if you need to.