Comments by Shvetsov Evgeniy (Top 21 by date)

Thanks for your answer! A kludge naturally built-in in the programming language is a very interesting phenomenon by itself :) Through C++ has more such a things: mutable AND friend, which breaks constness AND encapsulation.

Of course the compiler is NOT executing MY code directly, because MY code is in the C++ language, which is human-readable, while the CPU executes the machine code AND this machine code is the result of MY human-readable C++ code being transfered by the compiler to the machine code, this is pretty obvious really :))

Thanks for your reply! Putting the code into an external library (you're talkig about the dynamic lib., of course) is the possible way, yes, thank you!

Thanks for your reply! Of course it is. Sorry, but this all is just meaningles, there are plenty of examples of such a things, calculating factroial in compile time, evaluating str. len. etc. There is just NO way to "evaluate" OR "calculate" something WITHOUT executing code.

Thanks for your answer! Unfortunatly, it's not i was looking for, but anway still thank you!

1) This is lazy init, yes, there are plenty of ways how to implement singleton pattern (which is, in fact, applys the only restriction of one and single instance per any unit of execution time). The good example of how it can be done is shown in the wikipedia: https://en.wikipedia.org/wiki/Singleton_pattern#Example - there 5 (!) ways how to do that JAVA-way.

2) I understood what you're talking about, YES, we can set the instance private while proiding the public getter to access it, BUT there is just NO reson to do that when your singleton is a CONST. It's just meaningles in this case. Just minimalistic minimalistic way for implementation :)

1) volatile is NOT a recommendation, ofcourse not, never be, never was. I'l reccomend you familiarize yourself with this qualifier, as you currently clearly misundersttod it. Here is a good article: http://www.drdobbs.com/parallel/volatile-vs-volatile/212701484

2) There is, of course, dynamic singleton, which is, opposite to static, allocated and created on demand in run time.

3) My singleton realization is a simple "out of the box" solution, if you can proof you can properly create many instances of it, then show me how! :)

I'm sorry, but y're completly wrong here.

1) Here you can find an examples of how code runned compile time:

http://stackoverflow.com/questions/12108390/c11-compile-time-calculation-of-array
http://stackoverflow.com/questions/25890784/computing-length-of-a-c-string-at-compile-time-is-this-really-a-constexpr

2) The volatile keyword prevents optimization, as it tells the compiler to drop ANY assumptions which he maid among the volatile object, so free that object of optimizations.

"Basically, volatile announces that a value might change behind your program's back. That prevents compilers from caching the value (in a CPU register) and from optimizing away accesses to that value when they seem unnecessary from the POV of your program" - from http://stackoverflow.com/questions/3604569/what-kinds-of-optimizations-does-volatile-prevent-in-c

3) constexpr works diffrentley depending on what actually is marked "constexpr":

"constexpr function allows the function to be evaluated at compile time, but does not require that, so your answer is "maybe". It depends on the compiler's optimization settings. If you wish to have no runtime cost, you could force compile-time evaluation by assigning it to a constexpr variable" - from http://stackoverflow.com/questions/12785691/c-constexpr-at-compile-time?rq=1

Through we just completly reversed teacher/learner relationships here, stil thank you for your reply.

"Why" what? 9/8 gives 1,125 while 4/5 gives 0,8 and 2/1 gives 2.0, do y see there some 'infinity'? 64 bit IEE754 floating point gives only up to 15–17 significant decimal digits precision, so 1/3 as a decimal fraction can't be longer then 17 digits (as a number) anyway. I am upgrading a convertion module form my library and i want it to be implemented in the efficient way, thats exactly what i want.

But still, MS VS 2013, even fully updated (Community Update 5) miss that 'DBL_DECIMAL_DIG' constant, which isn't good. I guess that modern GCC or Intel compiler has no such problem.

Yes, i know that MS VS didn't support long double, but i am developing a portable code, so it doesn't matters. Any way, your answer is very clear, informative and usefull, thanks a lot, you completely solve my problem.

What the point of your meaningless comment and your negative vote?
The question is in the very first line and it is "MS VS 2013 'LDBL_DIG' const. From 'float.h' is incorrect?"

I want exactly what you talking about, but the next time original value would be 1.12 and the 100000 would't work. This is the first problem. The seond problem is that you can mangle the value that way (see 'What I have tried').

So i need a way to somehow transform a double value to integer value fastly and loosing nothing. I am assuming there should be some CPU inrinstic or somewhat similar to do that. If humnaity launches rockets i hope there way to do this too :))

'There is heaps of methods to transform a fractional part to an integer' - OK, what is the efficient then? DO you know how to do that involving the constant operations count?

Thx, but i already read those. The problem is that i need a fractional part NOT as a double (the standart 'modf' do this), i need it to be an integral number. Converting it to text and then back to number is too complicated. I looking for a much faster solution.

It was 'convert fractional part of a double to int' until edited. 123.321 had 123 as an integral part and 0.321 as a fractional part. I need to get int = 321, as example shows. The precision of any type is finit, so i need to convert it to an unsigned long long int without lossing precision and regardless of the digit's count (constant complexity).

Nope, the digits count is undetermined

I added an example, but the question itself is pretty straight and clear already..