StreamReader Class
Assembly: mscorlib (in mscorlib.dll)
StreamReader is designed for character input in a particular encoding, whereas the Stream class is designed for byte input and output. Use StreamReader for reading lines of information from a standard text file.
StreamReader defaults to UTF-8 encoding unless specified otherwise, instead of defaulting to the ANSI code page for the current system. UTF-8 handles Unicode characters correctly and provides consistent results on localized versions of the operating system.
By default, a StreamReader is not thread safe. See TextReader.Synchronized for a thread-safe wrapper.
The Read(Char[],Int32,Int32) and Write(Char[],Int32,Int32) method overloads read and write the number of characters specified by the count parameter. These are to be distinguished from BufferedStream.Read and BufferedStream.Write, which read and write the number of bytes specified by the count parameter. Use the BufferedStream methods only for reading and writing an integral number of byte array elements.
 Note: |
|---|
| When reading from a Stream, it is more efficient to use a buffer that is the same size as the internal buffer of the stream. |
For a list of common I/O tasks, see Common I/O Tasks.
The following code example uses a StreamReader object to read text from a file.
using System; using System.IO; class Test { public static void Main() { try { // Create an instance of StreamReader to read from a file. // The using statement also closes the StreamReader. using (StreamReader sr = new StreamReader("TestFile.txt")) { string line; // Read and display lines from the file until the end of // the file is reached. while ((line = sr.ReadLine()) != null) { Console.WriteLine(line); } } } catch (Exception e) { // Let the user know what went wrong. Console.WriteLine("The file could not be read:"); Console.WriteLine(e.Message); } } }
import System.*;
import System.IO.*;
class Test
{
public static void main(String[] args)
{
try {
// Create an instance of StreamReader to read from a file.
// The using statement also closes the StreamReader.
StreamReader sr = new StreamReader("TestFile.txt");
try {
String line;
// Read and display lines from the file until the end of
// the file is reached.
while ((line = sr.ReadLine()) != null) {
Console.WriteLine(line);
}
}
finally {
sr.Dispose();
}
}
catch (System.Exception e) {
// Let the user know what went wrong.
Console.WriteLine("The file could not be read:");
Console.WriteLine(e.get_Message());
}
} //main
} //Test
Windows 98, Windows Server 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 Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.