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StreamReader.Peek Method

Returns the next available character but does not consume it.

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

public override int Peek()

Return Value

Type: System.Int32
An integer representing the next character to be read, or -1 if there are no characters to be read or if the stream does not support seeking.

ExceptionCondition
IOException

An I/O error occurs.

The Peek method returns an integer value in order to determine whether the end of the file, or another error has occurred. This allows a user to first check if the returned value is -1 before casting it to a Char type.

The Peek method returns zero when the stream contains a byte with a value of zero.

This method overrides Peek.

The current position of the StreamReader object is not changed by Peek.

The following code example reads lines from a file until the end of the file is reached.

using System;
using System.IO;

class Test 
{
	
    public static void Main() 
    {
        string path = @"c:\temp\MyTest.txt";

        try 
        {
            if (File.Exists(path)) 
            {
                File.Delete(path);
            }

            using (StreamWriter sw = new StreamWriter(path)) 
            {
                sw.WriteLine("This");
                sw.WriteLine("is some text");
                sw.WriteLine("to test");
                sw.WriteLine("Reading");
            }

            using (StreamReader sr = new StreamReader(path)) 
            {

                while (sr.Peek() > -1) 
                {
                    Console.WriteLine(sr.ReadLine());
                }
            }
        } 
        catch (Exception e) 
        {
            Console.WriteLine("The process failed: {0}", e.ToString());
        }
    }
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

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