BinaryReader.ReadChars Method (System.IO)

Switch View :

ScriptFree

.NET Framework Class Library

BinaryReader.ReadChars Method

Reads the specified number of characters from the current stream, returns the data in a character array, and advances the current position in accordance with the Encoding used and the specific character being read from the stream.

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

Syntax

Visual Basic

Public Overridable Function ReadChars ( _
	count As Integer _
) As Char()

public virtual char[] ReadChars(
	int count
)

Visual C++

public:
virtual array<wchar_t>^ ReadChars(
	int count
)

abstract ReadChars : 
        count:int -> char[] 
override ReadChars : 
        count:int -> char[]

Parameters

count: Type: System.Int32
The number of characters to read.

Return Value

Type: System.Char[]
A character array containing data read from the underlying stream. This might be less than the number of characters requested if the end of the stream is reached.

Exceptions

Exception	Condition
ArgumentException	The number of decoded characters to read is greater than count. This can happen if a Unicode decoder returns fallback characters or a surrogate pair.
ObjectDisposedException	The stream is closed.
IOException	An I/O error occurs.
ArgumentOutOfRangeException	count is negative.

Remarks

BinaryReader does not restore the file position after an unsuccessful read operation.

When reading from network streams, in some rare cases, the ReadChars method might read an extra character from the stream if the BinaryReader was constructed with Unicode encoding. If this occurs, you can use the ReadBytes method to read a fixed-length byte array, and then pass that array to the ReadChars method.

Examples

The following code example shows how to read and write data using memory as a backing store.

Visual Basic


Imports System
Imports System.IO

Public Class BinaryRW

    Shared Sub Main()

        Dim invalidPathChars() As Char = Path.InvalidPathChars
        Dim memStream As new MemoryStream()
        Dim binWriter As New BinaryWriter(memStream)

        ' Write to memory.
        binWriter.Write("Invalid file path characters are: ")
        binWriter.Write(Path.InvalidPathChars)

        ' Create the reader using the same MemoryStream 
        ' as used with the writer.
        Dim binReader As New BinaryReader(memStream)

        ' Set Position to the beginning of the stream.
        memStream.Position = 0

        ' Read the data from memory and write it to the console.
        Console.Write(binReader.ReadString())
        Console.WriteLine(binReader.ReadChars( _
            CInt(memStream.Length - memStream.Position)))

	End Sub
End Class


using System;
using System.IO;

class BinaryRW
{
    static void Main()
    {
        char[] invalidPathChars = Path.InvalidPathChars;
        MemoryStream memStream = new MemoryStream();
        BinaryWriter binWriter = new BinaryWriter(memStream);

        // Write to memory.
        binWriter.Write("Invalid file path characters are: ");
        binWriter.Write(Path.InvalidPathChars);

        // Create the reader using the same MemoryStream 
        // as used with the writer.
        BinaryReader binReader = new BinaryReader(memStream);

        // Set Position to the beginning of the stream.
        memStream.Position = 0;

        // Read the data from memory and write it to the console.
        Console.Write(binReader.ReadString());
        Console.WriteLine(binReader.ReadChars(
            (int)(memStream.Length - memStream.Position)));
    }
}

Visual C++


using namespace System;
using namespace System::IO;
int main()
{
   array<Char>^invalidPathChars = Path::InvalidPathChars;
   MemoryStream^ memStream = gcnew MemoryStream;
   BinaryWriter^ binWriter = gcnew BinaryWriter( memStream );

   // Write to memory.
   binWriter->Write( "Invalid file path characters are: " );
   binWriter->Write( Path::InvalidPathChars );

   // Create the reader using the same MemoryStream 
   // as used with the writer.
   BinaryReader^ binReader = gcnew BinaryReader( memStream );

   // Set Position to the beginning of the stream.
   binReader->BaseStream->Position = 0;

   // Read the data from memory and write it to the console.
   Console::Write( binReader->ReadString() );
   Console::WriteLine( binReader->ReadChars( (int)(memStream->Length - memStream->Position) ) );
}

Version Information

.NET Framework

Supported in: 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

Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

Reference

BinaryReader Class

System.IO Namespace

Encoding

Other Resources

File and Stream I/O

How to: Read Text from a File

How to: Write Text to a File