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66.1 How do you persist any object in the registry?
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To store an object in the registry, the object should be serializable (either has a Serializable attribute attached to it or derives from ISerializable; same holds to all contained objects).
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ArrayList names; // Source object; Can contain any object that is serializable
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... // Fill up this arraylist
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BinaryFormatter formatter = new BinaryFormatter();
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MemoryStream stream1 = new MemoryStream();
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formatter.Serialize(stream1, names);
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... // Open the key where you want to store it, with write permissions
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regKey.SetValue("ValueName", stream1.ToArray());
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ArrayList names; // Destination object
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... // Open the corresponding key
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BinaryFormatter formatter = new BinaryFormatter();
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MemoryStream stream1 = new MemoryStream();
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barray1 = (byte[])regKey.GetValue("ValueName");
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stream1.Write(barray1, 0, barray1.Length);
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MemoryStream stream1 = new MemoryStream();
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barray1 = (byte[])regKey.GetValue("ValueName");
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stream1.Write(barray1, 0, barray1.Length);
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names = formatter.Deserialize(stream1) as ArrayList;
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66.2 How can I listen to changes in a file/directory in the windows file system?
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Use FileSystemWatcher to watch for changes in a specified directory. You can watch for changes in files and subdirectories of the specified directory. The component can watch files on a local computer, a network drive, or a remote computer.
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66.3 While deserializing how do I check whether a name is available in the deserialized info?
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This is usually an issue when a newer version introduces newer names, then the older version will not serialize property due to the absence of certain names. For example, this code will fail, sometimes:
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protected MyClassConstructor(SerializationInfo info, StreamingContext context)
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// This might fail if MyProp was added in a newer version and you are serializing an older version.
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this.MyProp = info.GetBoolean("MyProp");
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To avoid such conflicts, you could insert version nos. into the serialized info. and during deserialization check for a name only when a particular version is being deserialized. Or you could instead parse through the available info in the SerializationInfo list as follows:
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protected MyClassConstructor(SerializationInfo info, StreamingContext context)
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foreach(SerializationEntry entry in info)
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// This will make sure that older versions without the MyProp name will also deserialize without any problems
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this.MyProp = (bool)entry.Value;
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Protected MyClassConstructor(ByVal info As SerializationInfo, ByVal context As StreamingContext) As Protected
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Dim entry As SerializationEntry
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' This will make sure that older versions without the MyProp name will also deserialize without any problems
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Me.MyProp = (Boolean)entry.Value
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66.4 How come some of the objects are not initialized during deserialization?
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This is possible in this case: Say your object graph contains an object A, which has a reference to the object B. Then while deserializing A, the reference B might not be initialized yet. This is because while deserializing, references are deserialized one at a time and when A is deserialized, B might not have been deserialized, yet. You should follow the workaround as follows:
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protected MyCustomConstrucotr(SerializationInfo info, StreamingContext context)
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this.cachedRefToB = (B)info.GetValue("B", typeof(B));
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// At this point cachedRefToB might not be initialized.
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// But when this method gets called, after complete serialization, the cachedRefToB will be initialized
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void IDeserializationCallback.OnDeserialization(object sender)
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// At this point cachedRefToB will be initialized.
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protected MyCustomConstrucotr(ByVal info As SerializationInfo, ByVal context As StreamingContext) As Protected
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Me.cachedRefToB = CType(info.GetValue("B", Type.GetType(B)), B)
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' At this point cachedRefToB might not be initialized.
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' But when this method gets called, after complete serialization, the cachedRefToB will be initialized
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' Your class should implement IDeserializationCallback
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Sub OnDeserialization(ByVal sender As Object) as IDeserializationCallback.OnDeserialization
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' At this point cachedRefToB will be initialized.
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66.5 How can I access a webpage from a windows form?
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Use the WebRequest class found in the System.Net namespace.
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//create the request object
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WebRequest req = WebRequest.Create(@"http://www.syncfusion.com");
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//get the response and use the response
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WebResponse resp = req.GetResponse();
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Stream stream = resp.GetResponseStream();
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StreamReader sr = new StreamReader(stream);
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string s = sr.ReadToEnd();
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66.6 I just want to read a text file into a string. Is there some simple code for this?
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The following code reads a text file into a string object. It doesn't get any simpler than this. In production code always make sure that you handle exceptions.
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// filePath should contain the complete path to a file.
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StreamReader stream = new StreamReader(filePath);
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fileText = stream.ReadToEnd();
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66.7 I just want to write a simple text file. Is there some simple code for this?
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It doesn't get any simpler than this. In production code always make sure that you handle exceptions.
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// filePath has the complete path to the file
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StreamWriter writer = new StreamWriter(filePath);
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writer.Write(fileNewText);
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66.8 I want to iterate through both files and folders in a given folder. Is this possible?
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string[] contents = Directory.GetFileSystemEntries("folderName");
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foreach(string s in contents)
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66.9 My application requires a simple ini file. Is there a easy way to implement this without using any parsing?
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Yes. This may not be the most efficient way to read from a ini file but it is a pretty good solution that is easy to maintain.
You can use a XML file to store your settings. Use a DataSet to read from it. Consider a simple sample file, config.ini. It has three parameters base_path, update_path and output_file. These will map to columns in the settings datatable.
view config.ini
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DataSet ds = new DataSet();
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ds.ReadXml("config.ini", XmlReadMode.Auto);
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DataTable table = ds.Tables["settings"];
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DataRow row = table.Rows[0];
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string baseFolder = (string)row["base_path"];
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string updateFolder = (string)row["update_path"];
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string outputFileName = (string)row["output_file"];
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You can of course use XmlReader, XmlDocument etc to create and maintain more complex ini files. But this is a quick way to maintain a simple property set.
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66.10 How can I convert a long path to a short path?
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There is no direct support in the framework to do this. You have to use the GetShortPathName function using PInvoke.
This is how the signature for this function looks like:
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[DllImport("kernel32.dll", SetLastError=true, CharSet=CharSet.Auto)]
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public static extern int GetShortPathName(string longPath, [MarshalAs(UnmanagedType.LPTStr)]StringBuilder ShortPath, [MarshalAs(UnmanagedType.U4)]int bufferSize);
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