Close() vs. Dispose(): Which Method Should You Use for Stream Objects in C#?

Proper Disposal of Stream Objects: Close() vs. Dispose()

In programming, managing resources such as streams efficiently is crucial. Stream classes like Stream, StreamReader, and StreamWriter implement the IDisposable interface, presenting two methods for releasing resources: Close() and Dispose(). This article aims to clarify their roles and best practices.

Close() vs. Dispose()

The Close() method explicitly closes the stream, while the Dispose() method invokes the Dispose(bool) method, which internally handles resource release. The Close() method is inherited from the Stream class and is implemented differently for each derived stream type.

How they Work

Using the debugger or Reflector.NET, we can delve into the implementation of these methods. Both Close() methods eventually call Dispose(true), which frees resources and prevents further use of the object.

Best Practices

Given the equivalence of Close() and Dispose(), the choice boils down to readability.

• Using ( ... ) Block:

  • Guarantees resource release regardless of error conditions, promoting error handling consistency.
  • Can be difficult to identify the actual stream closure point due to multiple nested curly braces.

• Close() and Dispose() Combined:

  • Explicitly closes the stream using Close() after the using block ensures closure completion.
  • Clarifies the code structure and intention compared to using only Close().

Example

In the provided code snippet, using blocks are employed to ensure proper release. However, Close() methods are also called, which is not strictly necessary.

using (Stream responseStream = response.GetResponseStream())
{
    using (StreamReader reader = new StreamReader(responseStream))
    {
        using (StreamWriter writer = new StreamWriter(filename))
        {
            // Stream processing...
            writer.Close(); // Explicit close
        }
        reader.Close(); // Explicit close
    }
}

Recommendation

To enhance code readability, we recommend the following approach:

using (var stream = ...)
{
    /* code */

    stream.Close(); // Explicit close
}

This method combines the clarity of Close() with the resource release guarantee of the using block.

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