October 25, Pavia, Italy
November 6-8, Berlin, Germany
November 3-8, Kona, HI, USA
By Blog Staff | Feb 4, 2014 11:32 AM | Tags: basics
Quick A: Using the [] capture list.
Yesterday on SO:
Is it possible in C++11 / 14 syntax to write an lambda function which will see parent variables?
In abstraction:
int i = 1; auto go = [] () { return i; };Is it possible to make something like that in modern C++ syntax?
By Meeting C++ | Jan 29, 2014 07:47 AM | Tags: standardization performance intermediate experimental concurrency c++14 advanced
So I just started to read through the papers for the next C++ committee meeting in Issaquah in February, first part is about Concurrency:
C++ Papers for Issaquah -- Concurrency
by Jens Weller
From the article:
In february the C++ committee is going to meet for a week in Issaquah, it could be the final Meeting for C++14, the papers in this series will reflect both, C++14 and the standard that will come after it. Currently mostly known as C++1y. A lot of papers that are not part of C++14 will be formed into technical specifications, which some will then become C++1y later. Like the last series, I will again focus on the working groups, and post the papers sorted by the name of the working group, starting with concurrency.
By Blog Staff | Jan 27, 2014 03:06 PM | Tags: None
Quick A: Use raw string literals! If your compiler doesn't have them yet, nag.
The original question on SO, but note the best answer is pepper_chico's rather than the selected answer:
Only Detect Text in Quotations (C++)
I'm not great at programming and recently started to read tutorials on C++.
I decided I would attempt to make a simple blackjack program. I tried to make a title with "big text" but C++ is preventing me from doing it because it is detecting other things inside the text.
//Start Screen Begin cout << " ____ _ _ _ _ "; cout << "| __ )| | __ _ ___| | __(_) __ _ ___| | __ "; cout << "| _ \| |/ _` |/ __| |/ /| |/ _` |/ __| |/ / "; cout << "| |_) | | (_| | (__| < | | (_| | (__| < "; cout << "|____/|_|\__,_|\___|_|\_\/ |\__,_|\___|_|\_\ "; cout << " |__/ "; //Start Screen EndThis is what I am trying to display, yet keep getting the following error:
undefined reference to'WinMain@16'I am asking if there is a way to tell C++ I only want it to read and display the text, and not use any functions.
By Blog Staff | Jan 24, 2014 01:01 PM | Tags: None
From new C++ user groups springing up across Europe and upcoming conferences, to the Boost refactoring and (of course) C++14, Jens Weller has a nice piece previewing some of the things to look forward to for C++ in 2014.
C++ in 2014
by Jens Weller
Note that Jens' list is not complete, but it gives a pretty good overview of what's coming up in the near term with a few more things to be added later.
A small teaser from the article:
I already know that there are new C++ User Groups in Aachen, Dortmund, Heidelberg and Munich in Germany, also a Russian C++ User Group is now meeting in St. Petersburg and Moscow. I think a few others will follow...
By Blog Staff | Jan 24, 2014 09:32 AM | Tags: intermediate
Quick A: Maybe, but it generally commits you to exposing the internal type (can't change representation).
Recently on SO:
Should I use noexcept for getters always?
Should I use
noexceptmethod modifier for getters always in C++11?I mean simple getters here that just return members. At least in all my getters I have here an exception can't possibly be thrown. One downside is that a getter gets too verbose:
const std::string& getName() const noexcept{ return name; }The good side as pointed out in Stroustrup's book is that the compiler might do some optimizations here and there.
By Blog Staff | Jan 15, 2014 10:26 AM | Tags: intermediate
The solution to the latest GotW problem is now available:
GotW #95 Solution: Thread Safety and Synchronization
by Herb Sutter
From the article:
This GotW was written to answer a set of related frequently asked questions. So here’s a mini-FAQ on "thread safety and synchronization in a nutshell," and the points we’ll cover apply to thread safety and synchronization in pretty much any mainstream language.
By Blog Staff | Jan 14, 2014 08:49 AM | Tags: intermediate
.jpg)
In the current MSDN Magazine:
Using Regular Expressions with Modern C++
by Kenny Kerr
From the article:
C++11 introduced a long list of features that are in themselves quite exciting, but if all you see is a list of isolated features, then you’re missing out. The combination of these features makes C++ into the powerhouse that many have grown to appreciate. I’m going to illustrate this point by showing you how to use regular expressions with modern C++... the combination of C++ language and library features really turns C++ into a productive programming language.
By Blog Staff | Jan 14, 2014 06:54 AM | Tags: None
Quick A: Use a template alias. Several standard ones are coming in C++14.
Recently on SO:
How can I avoid writing
::valueand::typewhen usingstd::enable_if? [cppx]In some of my code, namely the header
rfc/cppx/text/String.h, I found the following mysterious snippet:template< class S, class enable = CPPX_IF_( Is_a_< String, S > ) > void operator! ( S const& ) { string_detail::Meaningless::operation(); }The
operator!is in support of aStringclass that has an implicit conversion to raw pointer. So I overload (among others)operator!for this class and derived classes, so that inadvertent use of a non-supported operator will give a suitable compilation error, mentioning that it's meaningless and inaccessible. Which I think is much preferable to such usage being silently accepted with an unexpected, incorrect result.The
CPPX_IF_macro supports Visual C++ 12.0 (2013) and earlier, which finds C++11 using to be mostly beyond its ken. For a more standard-conforming compiler I would have written just ...template< class S, class enable = If_< Is_a_< String, S > > > void operator! ( S const& ) { string_detail::Meaningless::operation(); }This looks like
std::enable_if,template< class S, class enabled = typename std::enable_if< Is_a_< String, S >::value, void >::type > void operator! ( S const& ) { string_detail::Meaningless::operation(); }except that the
If_orCPPX_IF_, and its expression, is much more concise and readable.How on Earth did I do that?
By Blog Staff | Jan 13, 2014 09:40 AM | Tags: intermediate
In part 4, Andrzej wraps up his series on type erasure with a discussion and comparison of facilities in the standard library, Boost, and otherwise.
Type Erasure, Part 4
by Andrzej Krzemieński
From the article:
In this post we will be wrapping up the series on type erasure. We will see an another form of value-semantic type erasure:
boost::any, and try to compare the different methods.
By Blog Staff | Jan 13, 2014 01:47 AM | Tags: basics
Quick A: It's a good style by default when you know you'll keep a copy of the parameter anyway. If you have an expensive-to-move type or otherwise want additional control, you can overload on &/&& or else perfect-forward.
Recently on SO:
Is the pass-by-value-and-then-move construct a bad idiom?
Since we have move semantincs in C++, nowadays it is usual to do
void set_a(A a) { _a = std::move(a); }The reasoning is that if
ais an rvalue, the copy will be elided and there will be just one move.But what happens if
ais an lvalue? It seems there will be a copy construction and then a move assignment (assumingAhas a proper move assignment operator). Move assignments can be costly if the object has too many member variables.On the other hand, if we do
void set_a(const A& a) { _a = a; }There will be just one copy assignment. Can we say this way is preferred over the pass-by-value idiom if we will pass lvalues?