create 2d barcode vb.net Implement an alternate Save method that uses the default file name. in Visual C#.NET

Printer Data Matrix 2d barcode in Visual C#.NET Implement an alternate Save method that uses the default file name.

Implement an alternate Save method that uses the default file name.
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public void Save() { // Assumes FileName is not null Save(this.FileName); }
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This code uses some classes we have not seen before, so let s break our main Save method down piece by piece. Our first line opens or creates the given file name as a FileStream object. This class provides file I/O using simple byte arrays, and supports the well-known standard in, standard out, and standard error streams familiar to C and C++ programmers. Files can be open in various modes (via the FileMode enumeration), with various access levels (via the FileAccess enumeration). Different sharing options can be specified as well (not shown here) via the FileShare enumeration.
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public void Save(string fileName) { FileStream fs = new FileStream(fileName, FileMode.Create, FileAccess.ReadWrite);
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Next, we create a StreamWriter instance using the new FileStream object. Since we are using strings and not byte arrays, we need a class that provides simple string operations. The StreamWriter class does just this, and includes a constructor that accepts a FileStream instance.
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StreamWriter sw = new StreamWriter(fs);
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COMMON FILE DIALOGS
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The new StreamWriter instance is used to write our data into the file. We encapsulate the code to write the actual data in a try block to catch any exception that might occur.
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try {
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First we write the version number as a string on the first line of the file. This line is a bit more magical than it looks. We are using a constant integer as an object here. While permitted, it requires the conversion of the value type _CurrentVersion into a reference type that can be treated as an object instance on the heap. This conversion is called boxing, since the value is boxed into a reference type on the heap. More information on boxing is provided in appendix A.
sw.WriteLine(_CurrentVersion.ToString());
The Photograph objects in the album are written using a foreach loop to iterate through the array. This code relies on the fact that our album contains Photograph objects and implements the IEnumerable interface. The WriteLine method from the StreamWriter class (actually, this method is inherited from the base TextWriter class) writes a given string onto a single line of the file and adds the appropriate line termination characters.
// Store each file on a separate line. foreach (Photograph photo in this) { sw.WriteLine(photo.FileName); }
You may think the magic of garbage collection obviates the need to explicitly clean up system resources such as files. As we have seen, this just isn t so. Normally the Dispose method is used to clean up nonmemory resources. For file objects such as FileStream and StreamWriter, the more traditional Close method is used. By definition, Close is equivalent to Dispose in the .NET Framework. Classes that provide a Close method are automatically disposed of when the Close method is called. We will discuss this notion in more detail in chapter 8. Since the files must be closed even when an exception occurs, we encapsulate these lines in a finally block. As you may know, while a finally block does not catch any exceptions, any code in the block is executed regardless of whether an exception occurs or not.
finally { sw.Close(); fs.Close(); } }
Note that closing the objects in the reverse order of which they were opened is critical. Once the FileWriter is closed, the StreamWriter is not able to write any SAVE FILE DIALOGS 185
remaining data into the file. Calling the Close methods in the proper order ensures all data is properly written to the file and avoids this potential error.
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In this book we take a rather straightforward approach to reading and writing files, and will stick with a simple text file to represent our album throughout the book. There are some summaries of using the System.IO namespace in the .NET documentation if you are interested in more details. Search for the Working with I/O section in the .NET Framework Developer s Guide. We could also have stored our file in XML using classes from the System.XML namespace. The use of XML, for eXtensible Markup Language, is a great way to organize data, and is particularly useful when interacting with database systems or interfacing with remote computer systems. We opted for a simple text file in our application since many readers may not be familiar with XML. You can read up on XML in general at www.xml.org, or look up the XmlReader class and other members of the System.XML namespace in the .NET documentation.
Our new Save method can now be used in our MyPhotos application to save an album via our Save and Save As menus. 6.6.2 SAVING AN ALBUM AS A NEW FILE Let s implement a handler for the Save As menu first. This handler should prompt the user to select a file where the album should be stored (using the SaveFileDialog class) and then use this file name to save the actual data. There are some questions to answer here about how photo albums should be saved. These questions apply more generally to any file, so are presented generically to apply to any file and not just our albums.
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