Quick Q: When is an rvalue evaluated?

By Adrien Hamelin | Jun 2, 2017 01:09 PM | Tags: intermediate c++11

Quick A: When it is assigned.

Recently on SO:

When is an rvalue evaluated?

s2 binds to the expression s1 + s1, but is this evaluated at the time s2 is assigned

Yes.

And also would s2 hold memory for a temporary string?

Precisely, s2 is bound to a temporary std::string.

s1 + s1 will produce a temporary std::string, which will be bound to the reference s2 (and its lifetime is extended to the lifetime of the reference). Then s2 += "Test";, performs operator+=() on  s2, i.e. the temporary std::string.

C++ User Group Meetings in June

By Meeting C++ | Jun 2, 2017 06:05 AM | Tags: user groups community

The monthly posting on upcoming C++ User Group Meetings:

C++ User Group meetings in June

by Jens Weller

From the article:

Again, in Summer time, many C++ User Groups meet to share an evening full of C++ with their local community! ...

C++ Online Compilers--Arne Mertz

By Adrien Hamelin | May 25, 2017 11:37 AM | Tags: community

Did you ever use them?

C++ Online Compilers

by Arne Mertz

From the article:

Online compilers can be useful tools to quickly compile a snippet of code without having to install a proper compiler on our computer. They can be especially useful to play with the newest language features, to share code snippets online or to compare different compilers...

A self-contained Pool in C++14--Jens Weller

By Adrien Hamelin | May 25, 2017 11:30 AM | Tags: performance c++14

How to do a pool?

A self-contained Pool in C++14

by Jens Weller

From the article:

During C++Now I started writing a small application, that plays around with dlibs face recognition features. More on this later, the program uses the QThreadPool, and some researched showed that calling dlib::get_frontal_face_detector() is a very expensive operation. So I decided to write a thread safe pool to share the face detection object between threads, only loading as many as needed. The main thread owns the pool which owns the detection objects...

Accelerating your C++ on GPU with SYCL -- Simon Brand

By TartanLlama | May 24, 2017 01:13 PM | Tags: performance

A post on writing GPGPU code in C++ using the SYCL standard from the Khronos group.

Accelerating your C++ on GPU with SYCL

By Simon Brand

From the article:

Leveraging the power of graphics cards for compute applications is all the rage right now in fields such as machine learning, computer vision and high-performance computing. Technologies like OpenCL expose this power through a hardware-independent programming model, allowing you to write code which abstracts over different architecture capabilities. The dream of this is “write once, run anywhere”, be it an Intel CPU, AMD discrete GPU, DSP, etc. Unfortunately, for everyday programmers, OpenCL has something of a steep learning curve; a simple Hello World program can be a hundred or so lines of pretty ugly-looking code. However, to ease this pain, the Khronos group have developed a new standard called SYCL, which is a C++ abstraction layer on top of OpenCL. Using SYCL, you can develop these general-purpose GPU (GPGPU) applications in clean, modern C++ without most of the faff associated with OpenCL.

C++Now 2017--Michael Park

By Adrien Hamelin | May 23, 2017 09:23 AM | Tags: experimental community

Trip report!

C++Now 2017

by Michael Park

From the article:

I just returned from C++Now 2017 in Aspen, CO. This was my second time attending the conference and it was just as amazing as last year. My girlfriend decided to come along this time, since Aspen is such a beautiful place. We flew into Denver, rented a car and took the beautiful 4-hour drive into Aspen. She was very happy ��. Strongly recommended...

A question about avoiding page faults the first time newly-allocated memory is accessed--Raymond Che

By Adrien Hamelin | May 23, 2017 09:17 AM | Tags: performance advanced

Complicated stuff, interesting also!

A question about avoiding page faults the first time newly-allocated memory is accessed

by Raymond Chen

From the article:

A customer had a question about memory allocation...

What the Curiously Recurring Template Pattern can bring to your code--Jonathan Boccara

By Adrien Hamelin | May 19, 2017 11:35 AM | Tags: advanced

Curious things!

What the Curiously Recurring Template Pattern can bring to your code

by Jonathan Boccara

From the article:

After having defined the basics on the CRTP in episode #1 of the series, let’s now consider how the CRTP can be helpful in day-to-day code...

Important semantic effects of small syntax errors -- Matt Wilson

By Andrzej Krzemienski | May 18, 2017 07:34 AM | Tags: basics

Every C++ programmer should see a bug like this, from Matthew Wilson's post.  As a warning.

Important semantic effects of small syntax errors

by Matt Wilson

Quick Q: Is list::size() really O(n)?

By Adrien Hamelin | May 16, 2017 12:38 PM | Tags: intermediate c++11

Quick A: In C++11 it's required to be constant time.

Recently on SO:

Is list::size() really O(n)?

In C++11 it is required that for any standard container the .size() operation must be complete in "constant" complexity (O(1)). (Table 96 — Container requirements). Previously in C++03 .size() should have constant complexity, but is not required (see Is std::string size() a O(1) operation?).

The change in standard is introduced by n2923: Specifying the complexity of size() (Revision 1).