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BinaryWriter.Write Method (String)

Writes a length-prefixed string to this stream in the current encoding of the BinaryWriter, and advances the current position of the stream in accordance with the encoding used and the specific characters being written to the stream.

Namespace:  System.IO
Assembly:  mscorlib (in mscorlib.dll)

public virtual void Write(
	string value
)

Parameters

value
Type: System.String

The value to write.

ExceptionCondition
IOException

An I/O error occurs.

ArgumentNullException

value is null.

ObjectDisposedException

The stream is closed.

Length-prefixed means that this method first writes the length of the string, in bytes, when encoded with the BinaryWriter instance's current encoding to the stream. This value is written as an unsigned integer. This method then writes that many bytes to the stream.

For example, the string “A” has a length of 1, but when encoded with UTF-16; the length is 2 bytes, so the value written in the prefix is 2, and 3 bytes are written to the stream, including the prefix.

For a list of common I/O tasks, see Common I/O Tasks.

The following code example demonstrates how to store and retrieve application settings in a file.

using System;
using System.IO;

class ConsoleApplication
{
    const string fileName = "AppSettings.dat";

    static void Main()
    {
        WriteDefaultValues();
        DisplayValues();
    }

    public static void WriteDefaultValues()
    {
        using (BinaryWriter writer = new BinaryWriter(File.Open(fileName, FileMode.Create)))
        {
            writer.Write(1.250F);
            writer.Write(@"c:\Temp");
            writer.Write(10);
            writer.Write(true);
        }
    }

    public static void DisplayValues()
    {
        float aspectRatio;
        string tempDirectory;
        int autoSaveTime;
        bool showStatusBar;

        if (File.Exists(fileName))
        {
            using (BinaryReader reader = new BinaryReader(File.Open(fileName, FileMode.Open)))
            {
                aspectRatio = reader.ReadSingle();
                tempDirectory = reader.ReadString();
                autoSaveTime = reader.ReadInt32();
                showStatusBar = reader.ReadBoolean();
            }

            Console.WriteLine("Aspect ratio set to: " + aspectRatio);
            Console.WriteLine("Temp directory is: " + tempDirectory);
            Console.WriteLine("Auto save time set to: " + autoSaveTime);
            Console.WriteLine("Show status bar: " + showStatusBar);
        }
    }
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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