What is standard layout?

A standard-layout type is a type with a simple linear data structure and access control that can easily be used to communicate with code written in other programming languages, such as C, either cv-qualified or not. This is true for scalar types, standard-layout classes and arrays of any such types.

What is trivial C++?

Trivial types When a class or struct in C++ has compiler-provided or explicitly defaulted special member functions, then it is a trivial type. It occupies a contiguous memory area. It can have members with different access specifiers. In C++, the compiler is free to choose how to order members in this situation.

What is a pod C++?

POD is an acronym in C++ that means plain old data. It is a class/struct that ONLY has member variables and no methods, constructors, destructors, virtual functions, etc.

Why is Is_pod deprecated?

“POD” is equivalent to “trivial and standard layout”, but for many code patterns, a narrower restriction to just “trivial” or just “standard layout” is appropriate; to encourage such precision, the notion of “POD” was therefore deprecated.

What is a trivial class?

A trivial class is a class (defined with class, struct or union) that is both trivially default constructible and trivially copyable, which implies that: uses the implicitly defined default, copy and move constructors, copy and move assignments, and destructor. has no virtual members.

What is a POD type?

A POD type (which stands for Plain Old Data type) is a type whose characteristics are supported by a data type in the C language, either cv-qualified or not. This includes scalar types, POD classes and arrays of any such types.

Is std :: string trivial?

You can’t use constexpr, because std::string does not have a trivial destructor. Check the requirements on cppreference.

Is a struct a POD?

a class , struct or union of PODs is a POD provided that all non-static data members are public , and it has no base class and no constructors, destructors, or virtual methods.

Is std :: array POD?

In C++03, POD was defined in terms of aggregate: a class where every subobject is native or an aggregate is POD. So, by backwards compatibility, a C++0x std::array is POD.

Is POD A STD?

std::is_pod Trait class that identifies whether T is a POD type. A POD type (which stands for Plain Old Data type) is a type whose characteristics are supported by a data type in the C language, either cv-qualified or not. This includes scalar types, POD classes and arrays of any such types.

Is POD A CPP?

A POD is a type (including classes) where the C++ compiler guarantees that there will be no “magic” going on in the structure: for example hidden pointers to vtables, offsets that get applied to the address when it is cast to other types (at least if the target’s POD too), constructors, or destructors.

Is a constructor a trivial?

A Trivial Default Constructor is a constructor that does not act. All data types compatible with the C are trivially default-constructible.

Is STD array a POD?

std::array is a POD type.

Is trivially constructible?

A trivially default constructible type is a type which can be trivially constructed without arguments or initialization values, either cv-qualified or not. This includes scalar types, trivially default constructible classes and arrays of such types.

Is trivially copyable?

A trivially copyable type is a type whose storage is contiguous (and thus its copy implies a trivial memory block copy, as if performed with memcpy), either cv-qualified or not. This is true for scalar types, trivially copyable classes and arrays of any such types.

Is Std a vector a POD?

std::is_pod is being deprecated, in accordance with the standard library moving away from the term POD as a whole. Also, the requirement that T must be a POD type is too strict; your vector will still work correctly if T is trivial.

Is pointer a POD?

pointers (including pointer-to-function and pointer-to-member) are PODs, enums are PODs. a const or volatile POD is a POD. a class , struct or union of PODs is a POD provided that all non-static data members are public , and it has no base class and no constructors, destructors, or virtual methods.

Is std :: array copyable?

Since C++11, we can directly copy std::array with the assignment operator or the copy constructor.

Is std :: array initialize?

std::array contains a built-in array, which can be initialized via an initializer list, which is what the inner set is. The outer set is for aggregate initialization.

Can you overload constructor?

Constructors can be overloaded in a similar way as function overloading. Overloaded constructors have the same name (name of the class) but the different number of arguments. Depending upon the number and type of arguments passed, the corresponding constructor is called.

What is a standard layout type?

Standard layout types are useful for communicating with code written in other programming languages. Note: the standard doesn’t define a named requirement with this name. This is a type category defined by the core language. It is included here as a named requirement only for consistency.

What determines the layout of a class in C++?

In some cases, the layout is well-defined by the language specification. But when a class or struct contains certain C++ language features such as virtual base classes, virtual functions, members with different access control, then the compiler is free to choose a layout.

Can the compiler choose the layout of a class or struct?

But when a class or struct contains certain C++ language features such as virtual base classes, virtual functions, members with different access control, then the compiler is free to choose a layout.

What are simple classes in C++14?

To enable compilers as well as C++ programs and metaprograms to reason about the suitability of any given type for operations that depend on a particular memory layout, C++14 introduced three categories of simple classes and structs: trivial, standard-layout, and POD or Plain Old Data.