C# returning from inside a using block

Question

will a construct like this, dispose the filehandle correctly?

void bla() {
    using (var stream = new new System.IO.StreamReader( filename)) {
        return DoSomethingWithTheStream(stream);
    }
}

i.e. will the using trigger the Dispose even though it is returned inside?

score 5 · Accepted Answer · answered Sep 19 '13 at 14:06

5

This is equivalent to:

var stream = new StreamReader(fileName);
try {
    return DoSomethingWithTheStream(stream);
}
finally {
    stream.Dispose();
}

Since finally clauses are guaranteed to execute, it's guaranteed that the stream is disposed before returning from the method.

answered Sep 19 '13 at 14:06

Asik

1

I love examples in reactions. Gives so much more about how it works. +1 – Jeroen van Langen Sep 19 '13 at 14:07

score 4 · Answer 2 · answered Sep 19 '13 at 14:01

4

Yes. No matter how the block is left, the resource is disposed. This is the value of the using-block.

answered Sep 19 '13 at 14:01

usr

score 2 · Answer 3 · answered Sep 19 '13 at 14:01

2

Yes, it will dispose correctly.

answered Sep 19 '13 at 14:01

Raidri

score 0 · Answer 4 · answered Sep 19 '13 at 14:03

0

Yes, as soon as stream goes out of scope it will be disposed.

answered Sep 19 '13 at 14:03

Gerrie Schenck

4 Answers4