TextReader.ReadLine Method (System.IO)

ReadLine Method

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Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

.NET Framework Class Library

TextReader..::.ReadLine Method

Updated: November 2007

Reads a line of characters from the current stream and returns the data as a string.

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

Syntax

Visual Basic (Declaration)

Public Overridable Function ReadLine As String

Visual Basic (Usage)

Dim instance As TextReader
Dim returnValue As String

returnValue = instance.ReadLine()

public virtual string ReadLine()

Visual C++

public:
virtual String^ ReadLine()

public String ReadLine()

JScript

public function ReadLine() : String

Return Value

Type: System..::.String

The next line from the input stream, or nullNothingnullptra null reference (Nothing in Visual Basic) if all characters have been read.

Exceptions

Exception	Condition
IOException	An I/O error occurs.
OutOfMemoryException	There is insufficient memory to allocate a buffer for the returned string.
ObjectDisposedException	The TextReader is closed.
ArgumentOutOfRangeException	The number of characters in the next line is larger than MaxValue

Remarks

A line is defined as a sequence of characters followed by a carriage return (0x000d), a line feed (0x000a), a carriage return followed by a line feed, Environment..::.NewLine, or the end of stream marker. The string that is returned does not contain the terminating carriage return and/or line feed. The returned value is nullNothingnullptra null reference (Nothing in Visual Basic) if the end of the input stream has been reached.

If the current method throws an OutOfMemoryException, the reader's position in the underlying Stream is advanced by the number of characters the method was able to read, but the characters already read into the internal ReadLine buffer are discarded. Since the position of the reader in the stream cannot be changed, the characters already read are unrecoverable, and can be accessed only by reinitializing the TextReader. If the initial position within the stream is unknown or the stream does not support seeking, the underlying Stream also needs to be reinitialized.

To avoid such a situation and produce robust code you should use the Read method and store the read characters in a preallocated buffer.

Platforms

Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, 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

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.

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