Will finally blocks be executed if returning from try or catch blocks in C#? If so, before returning or after?

Question

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Answer 1

Yes, the finally block is executed however the flow leaves the try block - whether by reaching the end, returning, or throwing an exception.

From the C# 4 spec, section 8.10:

The statements of a finally block are always executed when control leaves a try statement. This is true whether the control transfer occurs as a result of normal execution, as a result of executing a break, continue, goto, or return statement, or as a result of propagating an exception out of the try statement.

(Section 8.10 has a lot more detail on this, of course.)

Note that the return value is determined before the finally block is executed though, so if you did this:

int Test()
{
    int result = 4;
    try
    {
        return result;
    }
    finally
    {
        // Attempt to subvert the result
        result = 1;
    }
}

... the value 4 will still be returned, not 1 - the assignment in the finally block will have no effect.

Answer 2

A finally block will always be executed and this will happen before returning from the method, so you can safely write code like this:

try {
    return "foo";
} finally {
    // This will always be invoked
}

or if you are working with disposable resources:

using (var foo = GetFoo())
{
    // foo is guaranteed to be disposed even if an exception is thrown
    return foo.Bar();
}