TextReader.ReadLine Method

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

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

public virtual string ReadLine()

Return Value

Type: System.String
The next line from the input stream, or null if all characters have been read.

ExceptionCondition
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

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 null 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.

.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

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.
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