intermediate : Standard C++

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.

Using Regular Expressions with Modern C++ -- Kenny Kerr

By Blog Staff | Jan 14, 2014 08:49 AM | Tags: intermediate

dn519920.kenny_kerr_headshot(en-us,MSDN.10).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.

Type Erasure, Part 4 -- Andrzej Krzemieński

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.

GotW #7c Solution: Minimizing Compile-Time Dependencies, Part 3

By Blog Staff | Jan 8, 2014 10:32 AM | Tags: intermediate

The solution to the latest GotW problem is now available:

GotW #7c Solution: Minimizing Compile-Time Dependencies, Part 3

by Herb Sutter

From the article:

But did you notice the curious thing about B's virtual functions?

"What?" you might say. "B has no virtual functions."

Right. That is the curious thing...

Dive into C++11 (#4) — Smart pointers

By Vittorio Romeo | Jan 6, 2014 02:48 AM | Tags: intermediate

Hello once more isocpp users, I’m Vittorio Romeo, a computer science student, hobbyist game developer and C++ enthusiast.

I’ve uploaded the fourth episode of “Dive into C++11” on my YouTube channel.

After looking at C and C++'s memory and lifetime management in part 3, we'll take a brief look at C++11 smart pointers. We will learn what they are, what problem they solve, their advantages and their uses.

The intended audience for this tutorial/screencast are people who have some experience with C++ in general, and who watched the previous episodes. This episode may be very interesting for those with experience with C++ who want to learn more about variable lifetime and memory management.

I greatly appreciate comments and criticism, and ideas for future videos/tutorials.

Feel free to fork/analyze the source code at: https://github.com/SuperV1234/Tutorials

You can find the previous episodes here:

Episode 1
Episode 2
Episode 3
Playlist

Thanks for watching!

GotW #7b Solution: Minimizing Compile-Time Dependencies, Part 2

By Blog Staff | Jan 1, 2014 07:57 AM | Tags: intermediate basics

The solution to the latest GotW problem is now available.

GotW #7b Solution: Minimizing Compile-Time Dependencies, Part 2

by Herb Sutter

From the article:

Now that the unnecessary headers have been removed, it’s time for Phase 2: How can you limit dependencies on the internals of a class?

...
Guideline: For widely-included classes whose implementations may change, or to provide ABI-safety or binary compatibility, consider using the compiler-firewall idiom (Pimpl Idiom) to hide implementation details. Use an opaque pointer (a pointer to a declared but undefined class) declared as struct impl; std::unique_ptr<impl> pimpl; to store private nonvirtual members.

Quick Q: Does constexpr guarantee compile-time evaluation? -- StackOverflow

By Blog Staff | Dec 31, 2013 10:12 AM | Tags: intermediate

Quick A: constexpr guarantees compile-time evaluation is possible if operating on a compile-time value, and that compile-time evaluation will happen if a compile-time result is needed.

From SO, the originally worded question:

Can C++ constexpr function actually accept non-constant expression as argument?

I have defined a constexpr function as following:
constexpr int foo(int i)
{
    return i*2;
}
And this is what in the main function:
int main()
{
    int i=2;
    cout<<foo(i)<<endl;
    int arr[foo(i)];
    for(int j=0;j<foo(i);j++)
        arr[j]=j;
    for(int j=0;j<foo(i);j++)
        cout<<arr[j]<<" ";
    cout<<endl;
    return 0;
}
The program was compiled under OS X 10.8 with command clang++. I was surprised that the compiler did not produce any error message about foo(i) not being a constant expression, and the compiled program actually worked fine. Why?

Quick Q: How do I use conditional noexcept? -- StackOverflow

By Blog Staff | Dec 31, 2013 02:57 AM | Tags: intermediate

The question also has a lemon-zest touch of "templates in headers" but the basic noexcept question is still the same:

Use of the noexcept specifier in function declaration and definition?

Consider the following function:
// Declaration in the .h file
class MyClass
{
    template <class T> void function(T&& x) const;
};

// Definition in the .cpp file
template <class T> void MyClass::function(T&& x) const;
I want to make this function noexcept if the type T is nothrow constructible.

How to do that? (I mean what is the syntax ?)

Quick Q: Does memory layout (including alignment) matter for performance? -- StackOverflow

By Blog Staff | Dec 30, 2013 11:50 AM | Tags: intermediate

Quick A: Oh, yeah.

See the nice three-paragaph "highlights" answer to the question:

Does alignment really matter for performance in C++11?

There is an advice in Stroustrup's book to order the members in a struct beginning from the biggest to the smallest. But I wonder if someone has made measurements to actually see if this makes any difference, and if it is worth it to think about when writing code.