Using StringReader and StringWriter

For some applications it might be easier to use a string rather than a byte array for the underlying storage when performing memory-based I/O operations. When this is the case, use StringReader and StringWriter. StringReader inherits TextReader, and StringWriter inherits TextWriter. Thus, these streams have access to methods defined by those two classes. For example, you can call ReadLine( ) on a StringReader, and WriteLine( ) on a StringWriter.

The constructor for StringReader is shown here:

 StringReader(string str)

Here, str is the string that will be read from.

StringWriter defines several constructors. The one that we will use here is this:

 StringWriter( )

This constructor creates a writer that will put its output into a string. This string is automatically created by StringWriter. You can obtain the contents of this string by calling ToString( ).

Here is an example that uses StringReader and StringWriter:

 // Demonstrate StringReader and StringWriter using System; using System.IO; class StrRdrDemo {   public static void Main() {     // Create a StringWriter     StringWriter strwtr = new StringWriter();     // Write to StringWriter.     for(int i=0; i < 10; i++)        strwtr.WriteLine("This is i: " + i);     // Create a StringReader     StringReader strrdr = new StringReader(strwtr.ToString());     // Now, read from StringReader.     string str = strrdr.ReadLine();     while(str != null) {       str = strrdr.ReadLine();       Console.WriteLine(str);     }   } }

The output is shown here:

 This is i: 1 This is i: 2 This is i: 3 This is i: 4 This is i: 5 This is i: 6 This is i: 7 This is i: 8 This is i: 9

The program first creates a StringWriter called strwtr and outputs to it using WriteLine( ). Next, it creates a StringReader using the string contained in strwtr. This string is obtained by calling ToString( ) on strwtr. Finally, the contents of this string are read using ReadLine( ).