Bob Plantz <plantz@xxxxxxxx> writes: > I have often heard students say they were told that ++x is more > efficient than x++. From looking at gcc-generated assembly language, I > knew this is not always true. It's been pointed out here that the > situation is more "interesting" than I realized. For an integer type there is no performance difference between ++x and x++. For a C++ class which defines operator++ and a copy constructor, there can be performance differences between ++x and x++. The latter often requires the compiler to invoke the copy constructor to hold onto the old value before invoking operator++. So if you are writing C++, it's often a good idea to write ++x when x is a class type, such as an STL iterator. The compiler can sometimes eliminate the copy constructor, but not always. Ian
