c++

How do I pass a unique_ptr argument to a constructor or a function?

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Here are the possible ways to take a unique pointer as an argument, as well as their associated meaning. (A) By Value Base(std::unique_ptr<Base> n) : next(std::move(n)) {} In order for the user to call this, they must do one of the following: Base newBase(std::move(nextBase)); Base fromTemp(std::unique_ptr<Base>(new Base(…)); To take a unique pointer by value means … Read more

Struct Constructor in C++?

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In C++ the only difference between a class and a struct is that members and base classes are private by default in classes, whereas they are public by default in structs. So structs can have constructors, and the syntax is the same as for classes.

‘printf’ vs. ‘cout’ in C++

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I’m surprised that everyone in this question claims that std::cout is way better than printf, even if the question just asked for differences. Now, there is a difference – std::cout is C++, and printf is C (however, you can use it in C++, just like almost anything else from C). Now, I’ll be honest here; … Read more

Static linking vs dynamic linking

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Dynamic linking can reduce total resource consumption (if more than one process shares the same library (including the version in “the same”, of course)). I believe this is the argument that drives its presence in most environments. Here “resources” include disk space, RAM, and cache space. Of course, if your dynamic linker is insufficiently flexible … Read more

What are copy elision and return value optimization?

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Introduction For a technical overview – skip to this answer. For common cases where copy elision occurs – skip to this answer. Copy elision is an optimization implemented by most compilers to prevent extra (potentially expensive) copies in certain situations. It makes returning by value or pass-by-value feasible in practice (restrictions apply). It’s the only … Read more

What is Linux’s native GUI API?

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In Linux the graphical user interface is not a part of the operating system. The graphical user interface found on most Linux desktops is provided by software called the X Window System, which defines a device independent way of dealing with screens, keyboards and pointer devices. X Window defines a network protocol for communication, and … Read more

What are the differences between struct and class in C++?

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You forget the tricky 2nd difference between classes and structs. Quoth the standard (§11.2.2 in C++98 through C++11): In absence of an access-specifier for a base class, public is assumed when the derived class is declared struct and private is assumed when the class is declared class. And just for completeness’ sake, the more widely … Read more

Is there any advantage of using map over unordered_map in case of trivial keys?

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Don’t forget that map keeps its elements ordered. If you can’t give that up, obviously you can’t use unordered_map. Something else to keep in mind is that unordered_map generally uses more memory. map just has a few house-keeping pointers, and memory for each object. Contrarily, unordered_map has a big array (these can get quite big … Read more