What are the ways to use using keyword in C#?

What are the usages of using in C#, need specific code examples

In C#, the main purpose of using keyword is to ensure that after using a specific resource, it will be used in time. It is released or closed in order to promptly reclaim resources and maintain program performance. In addition to common file I/O resources, using can handle many other objects and resources. This article will introduce the common usage of using in C# and provide specific code examples.

1. File I/O resources:

using (StreamReader reader = new StreamReader("file.txt"))
{

string line = reader.ReadLine();
Console.WriteLine(line);

}
In the above code, use StreamReader to read a text file, and use using to ensure that the resource is closed and released after reading.

2. Database connection:

using (SqlConnection connection = new SqlConnection(connectionString))
{

connection.Open();
// 执行数据库操作

}
In this example , we use using and SqlConnection to ensure that the database connection is closed after completing the database operation.

3. Network resources:

using (WebClient client = new WebClient())
{

string result = client.DownloadString("http://www.example.com");
Console.WriteLine(result);

}
The above code uses using and WebClient to download and print the content of web pages.

4. Sound and graphics resources:

using (SoundPlayer player = new SoundPlayer("sound.wav"))
{

player.Play();
// 其他操作

}
In this example, we use using and SoundPlayer to play the sound file and ensure that the related resources are released after the playback is completed.

5. Thread locking:

using (Mutex mutex = new Mutex())
{

// 对共享资源进行操作

}
The above example uses using and Mutex to ensure that thread locks are released in time after operating on shared resources.

6. Memory resources:

using (MemoryStream stream = new MemoryStream())
{

// 使用内存流进行操作

}
In this example , we use using and MemoryStream to handle memory resources to ensure that related resources are released in time after use.

7. GDI resource:

using (Graphics g = Graphics.FromImage(bitmap))
{

// 对位图进行绘制操作

}
In the above In the code, using and Graphics are used to handle the drawing operation of the bitmap.

Summary:

The above are common usages of the using keyword in C# and corresponding code examples. It should be noted that using can only be used for classes that implement the IDisposable interface, which defines the Dispose method to release related resources. When using a using code block, there is no need to manually call the Dispose method. C# will automatically call the Dispose method at the end of the code block to ensure timely release of resources. This code structure not only makes the code more concise, but also reduces the risk of memory leaks and resource waste.

When using using, we also need to pay attention to exception handling. If an exception occurs in the using code block, the Dispose method may not be called, so a try-catch-finally structure is needed to ensure the release of resources.

In general, the using keyword in C# is a very useful language feature that can simplify resource management code and help the program maintain high performance and robustness. By using the using keyword appropriately, we can better manage and release various resources to ensure the correct operation of the program.

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