How to read a large (1 GB) txt file in .NET?

Question

I have a 1 GB text file which I need to read line by line. What is the best and fastest way to do this?

private void ReadTxtFile() {                 string filePath = string.Empty;     filePath = openFileDialog1.FileName;     if (string.IsNullOrEmpty(filePath))     {         using (StreamReader sr = new StreamReader(filePath))         {             String line;             while ((line = sr.ReadLine()) != null)             {                 FormatData(line);                                     }         }     } } 

In FormatData() I check the starting word of line which must be matched with a word and based on that increment an integer variable.

void FormatData(string line) {     if (line.StartWith(word))     {         globalIntVariable++;     } } 

Answer 1

If you are using .NET 4.0, try MemoryMappedFile which is a designed class for this scenario.

You can use StreamReader.ReadLine otherwise.