What does volatile guarantee?
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From: Arne Vajhøj on 15 Feb 2010 17:11 On 15-02-2010 15:05, Lew wrote: > Patricia Shanahan wrote: >> How frequently does ++ appear in typical Java programs? > > Rather a lot, I should think. > > for ( int ix = 0; ix < limit; ++ix ) ... > > int count = 0; > for ( Foo foo : foos ) > { > blahBlah(); > ++count; > } > > etc. > > Or did you mean specifically how often an atomic ++ for volatiles would > be needed? It seems likely that she is talking about the required atomic ++. BTW, isn't ++something a C++'ism? Arne
From: Lew on 15 Feb 2010 17:17 Arne Vajhøj wrote: > BTW, isn't ++something a C++'ism? It's been around longer than that, since C. -- Lew
From: Arne Vajhøj on 15 Feb 2010 17:48 On 15-02-2010 17:17, Lew wrote: > Arne Vajhøj wrote: >> BTW, isn't ++something a C++'ism? > > It's been around longer than that, since C. I know, but the ++something is better than something++ because it is faster is rooted in C++ classes I believe. Arne
From: Eric Sosman on 15 Feb 2010 18:18 On 2/15/2010 5:48 PM, Arne Vajhøj wrote: > On 15-02-2010 17:17, Lew wrote: >> Arne Vajhøj wrote: >>> BTW, isn't ++something a C++'ism? >> >> It's been around longer than that, since C. > > I know, but the ++something is better than something++ > because it is faster is rooted in C++ classes I believe. When I actually want the value of the expression, I write whichever I need (usually a[x++] or a[--x]). When all I want is the side-effect, I write ++x because "increment x" seems to read more smoothly than "x increment." In neither case do I waste even one deci-neuron's worth of brain power on the question of which is faster -- or which was once said to have been found to be faster by someone whom the sayer didn't actually know but had heard about from someone else who might possibly have known the experimenter's second cousin's first wife's roommate. -- Eric Sosman esosman(a)ieee-dot-org.invalid
From: Mike Schilling on 15 Feb 2010 18:28
Arne Vajh�j wrote: > On 15-02-2010 17:17, Lew wrote: >> Arne Vajh�j wrote: >>> BTW, isn't ++something a C++'ism? >> >> It's been around longer than that, since C. > > I know, but the ++something is better than something++ > because it is faster is rooted in C++ classes I believe. Right, in classes which overload '++". y = ++x + z; simply calls the ++ method and add z to the result, while y = x++ + z; needs to make a copy of x, add z to it, assign the result to y, and then call the ++ method on the "real" x. Depending on how complicated "x" is, the copy may be a significant expense. |