Add a new console application project named Ch10_Streams.

In Visual Studio 2017, set the solution's start-up project to be the current selection.

Import the System.IO and System.Xml namespaces, statically import the System.Console type, and add the following statement to the Main method:

    // define an array of strings 
    string[] callsigns = new string[] { "Husker", "Starbuck",
    "Apollo", "Boomer", "Bulldog", "Athena", "Helo", "Racetrack" }; 
 
    // define a file to write to using a text writer helper  
    string textFile = @"/Users/markjprice/Code/Ch10_Streams.txt"; 
    // string textFile = @"C:CodeCh10_Streams.txt"; // Windows 
    StreamWriter text = File.CreateText(textFile); 
 
    // enumerate the strings writing each one to the stream 
    foreach (string item in callsigns) 
    { 
      text.WriteLine(item); 
    } 
    text.Dispose(); // close the stream 
 
    // output all the contents of the file to the Console 
    WriteLine($"{textFile} contains {new FileInfo(textFile).Length}
    bytes."); 
    WriteLine(File.ReadAllText(textFile)); 
 
    // define a file to write to using the XML writer helper 
    string xmlFile = @"/Users/markjprice/Code/Ch10_Streams.xml"; 
    // string xmlFile = @"C:CodeCh10_Streams.xml"; 
 
    FileStream xmlFileStream = File.Create(xmlFile); 
    XmlWriter xml = XmlWriter.Create(xmlFileStream,  
      new XmlWriterSettings { Indent = true }); 
 
    // write the XML declaration 
    xml.WriteStartDocument(); 
  
    // write a root element 
    xml.WriteStartElement("callsigns"); 
 
    // enumerate the strings writing each one to the stream 
    foreach (string item in callsigns) 
    { 
      xml.WriteElementString("callsign", item); 
    } 
 
    // write the close root element 
    xml.WriteEndElement(); 
    xml.Dispose(); 
    xmlFileStream.Dispose(); 
 
    // output all the contents of the file to the Console 
    WriteLine($"{xmlFile} contains {new FileInfo(xmlFile).Length}
    bytes."); 
    WriteLine(File.ReadAllText(xmlFile)); 

Run the console application and view the output:

C:CodeCh10_Streams.txt contains 68 bytes.
Husker
Starbuck
Apollo
Boomer
Bulldog
Athena
Helo
Racetrack
C:CodeCh10_Streams.xml contains 320 bytes.
<?xml version="1.0" encoding="utf-8"?>
<callsigns>
<callsign>Husker</callsign>
<callsign>Starbuck</callsign>
 <callsign>Apollo</callsign>
 <callsign>Boomer</callsign>
 <callsign>Bulldog</callsign>
<callsign>Athena</callsign>
<callsign>Helo</callsign>
 <callsign>Racetrack</callsign>
</callsigns>

XML is relatively verbose, so it takes up more space in bytes than plain text. We can squeeze the XML using a common compression algorithm known as GZIP.

Import the following namespace:

    using System.IO.Compression; 

Add the following code to the end of the Main method:

    // compress the XML output 
    string gzipFilePath = @"/Users/markjprice/Code/Ch10.gzip"; 
    // string gzipFilePath = @"C:CodeCh10.gzip"; // Windows 
 
    FileStream gzipFile = File.Create(gzipFilePath); 
    GZipStream compressor = new GZipStream(gzipFile,
    CompressionMode.Compress); 
    XmlWriter xmlGzip = XmlWriter.Create(compressor); 
    xmlGzip.WriteStartDocument(); 
    xmlGzip.WriteStartElement("callsigns"); 
    foreach (string item in callsigns) 
    { 
      xmlGzip.WriteElementString("callsign", item); 
    } 
    xmlGzip.Dispose(); 
    compressor.Dispose(); // also closes the underlying stream 
 
    // output all the contents of the compressed file to the Console 
    WriteLine($"{gzipFilePath} contains {new
    FileInfo(gzipFilePath).Length} bytes."); 
    WriteLine(File.ReadAllText(gzipFilePath));  
 
    // read a compressed file 
    WriteLine("Reading the compressed XML file:"); 
    gzipFile = File.Open(gzipFilePath, FileMode.Open); 
    GZipStream decompressor = new GZipStream(gzipFile,
    CompressionMode.Decompress); 
    XmlReader reader = XmlReader.Create(decompressor); 
    while (reader.Read()) 
    { 
      // check if we are currently on an element node named callsign 
      if ((reader.NodeType == XmlNodeType.Element) && (reader.Name ==
      "callsign")) 
      { 
        reader.Read(); // move to the Text node inside the element 
        WriteLine($"{reader.Value}"); // read its value 
      } 
    } 
    reader.Dispose(); 
    decompressor.Dispose(); 

Rerun the application and notice that the compressed XML is less than half the size of the same XML without compression:

C:CodeCh10.gzip contains 150 bytes.
▼     ♦ 
{?{??}En?BYjQqf~???????Bj^r~Jf^??RiI??????MrbNNqfz^1?i?QZ??Zd?☼↨@H♣?$
▬%?
&gc?t,?????*????H?????t?&?d??%b??H?aUPbrjIQ"?←?◄?♦ ??9→∟:)
Reading the compressed XML file:
Husker
Starbuck
Apollo
Boomer
Bulldog
Athena
Helo
Racetrack