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StringReader.ReadLine Method

Reads a line from the underlying string.

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

public override string ReadLine ()
public String ReadLine ()
public override function ReadLine () : String

Return Value

The next line from the underlying string, or a null reference (Nothing in Visual Basic) if the end of the underlying string is reached.

Exception typeCondition

ObjectDisposedException

The current reader is closed.

OutOfMemoryException

There is insufficient memory to allocate a buffer for the returned string.

This method overrides the TextReader.ReadLine method.

A line is defined as a sequence of characters followed by a carriage return ("\r"), a line feed ("\n"), or a carriage return immediately followed by a line feed. The resulting string does not contain the terminating carriage return and/or line feed. The returned value is a null reference (Nothing in Visual Basic) if the end of the underlying string has been reached.

If the current method throws an OutOfMemoryException, the reader's position in the underlying string is advanced by the number of characters the method was able to read, and the characters already read into the internal ReadLine buffer are discarded. Since the position of the reader in the string cannot be changed, the characters already read are unrecoverable, and can be accessed only by reinitializing the StringReader. To avoid such a situation and produce robust code you should use the Read method and store the read characters in a preallocated buffer.

The following table lists examples of other typical or related I/O tasks.

To do this...

See the example in this topic...

Create a text file.

How to: Write Text to a File

Write to a text file.

How to: Write Text to a File

Read from a text file.

How to: Read Text from a File

Append text to a file.

How to: Open and Append to a Log File

File.AppendText

FileInfo.AppendText

Get the size of a file.

FileInfo.Length

Get the attributes of a file.

File.GetAttributes

Set the attributes of a file.

File.SetAttributes

Determine if a file exists.

File.Exists

Read from a binary file.

How to: Read and Write to a Newly Created Data File

Write to a binary file.

How to: Read and Write to a Newly Created Data File

This code example is part of a larger example provided for the StringReader class.

// From textReaderText, create a continuous paragraph 
// with two spaces between each sentence.
string aLine, aParagraph = null;
StringReader strReader = new StringReader(textReaderText);
while(true)
{
    aLine = strReader.ReadLine();
    if(aLine != null)
    {
        aParagraph = aParagraph + aLine + " ";
    }
    else
    {
        aParagraph = aParagraph + "\n";
        break;
    }
}
Console.WriteLine("Modified text:\n\n{0}", aParagraph);

// From textReaderText, create a continuous paragraph 
// with two spaces between each sentence.
String aParagraph = "";
String aLine;
StringReader strReader = new StringReader(textReaderText);
while (true) {
    aLine = strReader.ReadLine();
    if (aLine != null) {
        aParagraph = aParagraph + aLine + " ";
    }
    else {
        aParagraph = aParagraph + "\n";
        break ;
    }
}
Console.WriteLine("Modified text:\n\n{0}", aParagraph);

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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