When you lie to your compiler, don’t be surprised to get results those differ from what you expect.

In this case, the coder promised his/her compiler the value of “value” won’t be changed, as it was declared const.

Therefore our best friend (yes, the compiler) who trusted the coder, thought “hey, I could cache this value in a register and not fetch it from RAM every time I reference it”, i.e. optimization.

If we change the code in the link slightly, so that function funcC would print *value before the assignment, one would see that the value of *value had actually been modified by function funcA. However, the modification was not visible in main, because the compiler was lied to as the coder explicitly told it that there would be no modification to value.

In the body of function funcC, though value was declared as a pointer to const instance, the compiler was smart enough to know it was lied to. There was a const_cast and a assignment, therefore, the modification to *value was reflected in the output.

我的媽呀~~

在舊金山機場等回台北的飛機, 電視上不斷的播放著德州美軍基地內部發生槍擊的新聞.

CNN 目前的說法是: 連同兇手總共掛了 12 個人, 兇嫌是一名現役中校.

It is true that C++ provides programming constructs those consume more CPU cycles than it would when done without higher level of abstractions. But, hey, that’s the cost of abstractions, why pay when they are not needed?

Stop laying out your C++ design like Java. Avoid inheritance when possible. Don’t make every member function and destructor virtual without really thinking. They not only increase your run time overhead, they boost the complexity (read coupling) of your code like nothing else.

C++ does every C-style stuff the same way as C does. Not to mention it is capable of more compile time computation than C. I just fail to see how C++ could be slower than C in run time, seriously.