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How to: Read and Write to a Newly Created Data File 

The BinaryWriter and BinaryReader classes are used for writing and reading data, rather than character strings. The following code example demonstrates writing data to and reading data from a new, empty file stream (Test.data). After creating the data file in the current directory, the associated BinaryWriter and BinaryReader are created, and the BinaryWriter is used to write the integers 0 through 10 to Test.data, which leaves the file pointer at the end of the file. After setting the file pointer back to the origin, the BinaryReader reads out the specified content.


using System;
using System.IO;
class MyStream 
    private const string FILE_NAME = "Test.data";
    public static void Main(String[] args) 
        // Create the new, empty data file.
        if (File.Exists(FILE_NAME)) 
            Console.WriteLine("{0} already exists!", FILE_NAME);
        FileStream fs = new FileStream(FILE_NAME, FileMode.CreateNew);
        // Create the writer for data.
        BinaryWriter w = new BinaryWriter(fs);
        // Write data to Test.data.
        for (int i = 0; i < 11; i++) 
            w.Write( (int) i);
        // Create the reader for data.
        fs = new FileStream(FILE_NAME, FileMode.Open, FileAccess.Read);
        BinaryReader r = new BinaryReader(fs);
        // Read data from Test.data.
        for (int i = 0; i < 11; i++) 

Robust Programming

If Test.data already exists in the current directory, an IOException is thrown. Use FileMode.Create to always create a new file without throwing an IOException.

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