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Rick Marshall wrote: > The implication is that Java can create a sequence of instructions that > C can't. Essentially it can. Runtime (JIT) optimizers know things static optimizers don't. They can sometimes tell that a particular code path will not be taken or that an object has a certain type or other useful information that is simply not known to the static, compile-time optimizer. They can sometimes use such information to run even more quickly. The nature of the languages also plays a part. Pointer aliasing is a big problem for C and C++ optimizers. It's a reason Fortran outperforms C, even with the same compiler. Java doesn't have C-style pointers so it's more like Fortran in that regard. And of course manual memory allocation is almost always slower and less reliable than a good garbage collection library. You can use a garbage collection library for C/C++, but few programmers do in practice. Together these are enough to push Java a couple of percentage points ahead of C on some problems. Not all problems, certainly, but enough of them that you can't just naively assert that C must be faster than Java. That may have been true in 1997. Today it demonstrably isn't. -- Elliotte Rusty Harold elharo@m... Java I/O 2nd Edition Just Published! http://www.cafeaulait.org/books/javaio2/ http://www.amazon.com/exec/obidos/ISBN=0596527500/ref=nosim/cafeaulaitA/
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