Should I call Close or Dispose for stream objects

Question

Classes such as Stream  StreamReader  StreamWriter etc implements IDisposable interface  That means  we can call Dispose   method on objects of these classes  They ve also defined a public method called Close    Now that confuses me  as to what should I call once I m done with objects  What if I call both    My current code is this   using  Stream responseStream   response GetResponseStream         using  StreamReader reader   new StreamReader responseStream              using  StreamWriter writer   new StreamWriter filename                    int chunkSize   1024           while   reader EndOfStream                         char   buffer   new char chunkSize               int count   reader Read buffer  0  chunkSize               if  count    0                               writer Write buffer  0  count                                     writer Close                  reader Close             As you see  I ve written using   constructs  which automatically call Dispose   method on each object  But I also call Close   methods  Is it right   Please suggest me the best practices when using stream objects   -   MSDN example doesn t use using   constructs  and call Close   method    How to  Download Files with FTP   Is it good

User · Answer

The documentation says that these two methods are equivalent:

StreamReader.Close: This implementation of Close calls the Dispose method passing a true value.

StreamWriter.Close: This implementation of Close calls the Dispose method passing a true value.

Stream.Close: This method calls Dispose, specifying true to release all resources.

So, both of these are equally valid:

/* Option 1, implicitly calling Dispose */
using (StreamWriter writer = new StreamWriter(filename)) { 
   // do something
} 

/* Option 2, explicitly calling Close */
StreamWriter writer = new StreamWriter(filename)
try {
    // do something
}
finally {
    writer.Close();
}

Personally, I would stick with the first option, since it contains less "noise".

User · Answer

No  you shouldn t call those methods manually  At the end of the using block the Dispose   method is automatically called which will take care to free unmanaged resources  at least for standard  NET BCL classes such as streams  readers writers        So you could also write your code like this   using  Stream responseStream   response GetResponseStream        using  StreamReader reader   new StreamReader responseStream           using  StreamWriter writer   new StreamWriter filename                         int chunkSize   1024              while   reader EndOfStream                                 char   buffer   new char chunkSize                    int count   reader Read buffer  0  chunkSize                    if  count    0                                          writer Write buffer  0  count                                                 The Close   method calls Dispose

User · Answer

This is an old question  but you can now write using statements without needing to block each one  They will be disposed of in reverse order when the containing block is finished   using var responseStream   response GetResponseStream    using var reader   new StreamReader responseStream   using var writer   new StreamWriter filename    int chunkSize   1024  while   reader EndOfStream        char   buffer   new char chunkSize       int count   reader Read buffer  0  chunkSize       if  count    0                writer Write buffer  0  count             https   docs microsoft com en-us dotnet csharp language-reference proposals csharp-8 0 using

User · Answer

On many classes which support both Close   and Dispose   methods  the two calls would be equivalent   On some classes  however  it is possible to re-open an object which has been closed   Some such classes may keep some resources alive after a Close  in order to permit reopening  others may not keep any resources alive on Close    but might set a flag on Dispose   to explicitly forbid re-opening   The contract for IDisposable Dispose explicitly requires that calling it on an object which will never be used again will be at worst harmless  so I would recommend calling either IDisposable Dispose or a method called Dispose   on every IDisposable object  whether or not one also calls Close

User · Answer

For what it s worth  the source code for Stream Close explains why there are two methods      Stream used to require that all cleanup logic went into Close       which was thought up before we invented IDisposable   However  we    need to follow the IDisposable pattern so that users can write    sensible subclasses without needing to inspect all their base    classes  and without worrying about version brittleness  from a    base class switching to the Dispose pattern   We re moving    Stream to the Dispose bool  pattern - that s where all subclasses    should put their cleanup now    In short  Close is only there because it predates Dispose  and it can t be deleted for compatibility reasons

User · Answer

A quick jump into Reflector NET shows that the Close   method on StreamWriter is   public override void Close         this Dispose true       GC SuppressFinalize this       And StreamReader is   public override void Close         this Dispose true       The Dispose bool disposing  override in StreamReader is   protected override void Dispose bool disposing        try               if   this Closable  amp  amp  disposing   amp  amp   this stream    null                         this stream Close                        finally               if  this Closable  amp  amp   this stream    null                         this stream   null                 deleted for brevity                base Dispose disposing                       The StreamWriter method is similar   So  reading the code it is clear that that you can call Close    amp  Dispose   on streams as often as you like and in any order  It won t change the behaviour in any way   So it comes down to whether or not it is more readable to use Dispose    Close   and or using                   My personal preference is that using                 should always be used when possible as it helps you to  not run with scissors    But  while this helps correctness  it does reduce readability  In C  we already have plethora of closing curly braces so how do we know which one actually performs the close on the stream   So I think it is best to do this   using  var stream                 code         stream Close        It doesn t affect the behaviour of the code  but it does aid readability

[c#] Should I call Close() or Dispose() for stream objects?

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