> Is that actually guaranteed by the standard? Kinda sorta. Technically, the program runs on an abstract machine, and the compiler is free to do whatever it wa

> Is that actually guaranteed by the standard? Kinda sorta. Technically, the program runs on an abstract machine, and the compiler is free to do whatever it wants that has the same observable behavior as the code you wrote. But this is not really a problem in practice: You will get what ask for, or occasionally the optimizer will give you something even better. If you really need to ensure that you have exactly the layout you ask for, you could use "volatile" which tells the compiler that some region of memory is "special". Storing stuff there could have side effects. The memory could change at any time. This will force the compiler to follow your instruction verbatim. But it's not really advised since it will read the data from memory every time even if it's available for quick and easy access in a register - the memory could have changed, better read it again! One important thing that is not possible to express in C++, is that some value, e.g. a password, should be purged from memory. A copy of the password in some random location of memory, that is not observable, so the compiler is free to create such a copy if it wants to.