My guess is, that in the first case two different branches end up in the same branch-prediction slot on the CPU. If these two branches predict different each time the code will slow down. In the second loop, the added code may just be enough to move one of the branches to a different branch … Read more
Neil Butterworth, Mark and Pavel are right. SQUARE(++y) expands to ++y * ++y, which increments twice the value of y. Another problem you could encounter: SQUARE(a + b) expands to a + b * a + b which is not (a+b)*(a+b) but a + (b * a) + b. You should take care of adding … Read more
What are precompiled headers? Often C++ source files include headers from external libraries. In Windows you include windows.h. These header files can be very large and they take some time to process. Each time you compile a C++ file the compiler has to read and process thousands of lines from these header files. But external … Read more
Try this MSDN page: Macros for Build Commands and Properties
VC6 was non-compliant by default in this regard. VC6’s new returned 0 (or NULL). Here’s Microsoft’s KB Article on this issue along with their suggested workaround using a custom new handler: Operator new does not throw a bad_alloc exception on failure in Visual C++ If you have old code that was written for VC6 behavior, … Read more