非常非正式地:

POD是一种类型(包括类)，c++编译器保证结构中不会发生“魔法”:例如，指向虚表的隐藏指针，转换为其他类型时应用于地址的偏移量(至少如果目标也是POD)，构造函数或析构函数。粗略地说，当类型中只有内置类型和它们的组合时，类型就是POD。结果是某种“像”C类型的东西。

非正式地:

int, char, wchar_t, bool, float, double are PODs, as are long/short and signed/unsigned versions of them. 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. Static members don't stop something being a POD under this rule. This rule has changed in C++11 and certain private members are allowed: Can a class with all private members be a POD class? Wikipedia is wrong to say that a POD cannot have members of type pointer-to-member. Or rather, it's correct for the C++98 wording, but TC1 made explicit that pointers-to-member are POD.

形式上(c++ 03标准):

3.9(10): "Arithmetic types (3.9.1), enumeration types, pointer types, and pointer to member types (3.9.2) and cv-qualified versions of these types (3.9.3) are collectively caller scalar types. Scalar types, POD-struct types, POD-union types (clause 9), arrays of such types and cv-qualified versions of these types (3.9.3) are collectively called POD types" 9(4): "A POD-struct is an aggregate class that has no non-static data members of type non-POD-struct, non-POD-union (or array of such types) or reference, and has no user-define copy operator and no user-defined destructor. Similarly a POD-union is an aggregate union that has no non-static data members of type non-POD-struct, non-POD-union (or array of such types) or reference, and has no user-define copy operator and no user-defined destructor. 8.5.1(1): "An aggregate is an array or class (clause 9) with no user-declared constructors (12.1), no private or protected non-static data members (clause 11), no base classes (clause 10) and no virtual functions (10.3)."

POD代表普通旧数据——也就是说，一个没有构造函数、析构函数和虚成员函数的类(无论是用关键字struct还是用关键字class定义的)。维基百科关于POD的文章更详细一些，并将其定义为:

c++中的普通旧数据结构是一个聚合类，它只包含PODS作为成员，没有用户定义的析构函数，没有用户定义的复制赋值操作符，也没有指针到成员类型的非静态成员。

更多的细节可以在c++ 98/03的答案中找到。c++ 11改变了围绕POD的规则，极大地放松了它们，因此需要在这里进行后续回答。

普通旧数据

简而言之，它是所有内置数据类型(例如int、char、float、long、unsigned char、double等)和POD数据的所有聚合。是的，这是递归定义。；）

更清楚地说，POD就是我们所说的“结构体”:仅存储数据的单元或单元组。

POD(普通旧数据)对象具有这些数据类型中的一种——基本类型、指针、联合、结构、数组或类——没有构造函数。相反，非pod对象是存在构造函数的对象。POD对象在获得与其类型对应的适当大小的存储空间时开始其生命周期，在对象的存储空间被重用或释放时结束其生命周期。

PlainOldData类型也不能包含:

虚函数(它们自己的或继承的) 虚拟基类(直接或间接)。

PlainOldData更宽松的定义包括带有构造函数的对象;但不包括那些虚拟的东西。PlainOldData类型的重要问题是它们是非多态的。继承可以用POD类型完成，但是它应该只用于ImplementationInheritance(代码重用)，而不是多态性/子类型。

一个常见的(虽然不是严格正确的)定义是PlainOldData类型是没有VeeTable的任何类型。

POD的概念和类型特征std::is_pod将在c++ 20中被弃用。有关进一步信息，请参阅此问题。

非常非正式地:

POD是一种类型(包括类)，c++编译器保证结构中不会发生“魔法”:例如，指向虚表的隐藏指针，转换为其他类型时应用于地址的偏移量(至少如果目标也是POD)，构造函数或析构函数。粗略地说，当类型中只有内置类型和它们的组合时，类型就是POD。结果是某种“像”C类型的东西。

非正式地:

int, char, wchar_t, bool, float, double are PODs, as are long/short and signed/unsigned versions of them. 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. Static members don't stop something being a POD under this rule. This rule has changed in C++11 and certain private members are allowed: Can a class with all private members be a POD class? Wikipedia is wrong to say that a POD cannot have members of type pointer-to-member. Or rather, it's correct for the C++98 wording, but TC1 made explicit that pointers-to-member are POD.

形式上(c++ 03标准):

3.9(10): "Arithmetic types (3.9.1), enumeration types, pointer types, and pointer to member types (3.9.2) and cv-qualified versions of these types (3.9.3) are collectively caller scalar types. Scalar types, POD-struct types, POD-union types (clause 9), arrays of such types and cv-qualified versions of these types (3.9.3) are collectively called POD types" 9(4): "A POD-struct is an aggregate class that has no non-static data members of type non-POD-struct, non-POD-union (or array of such types) or reference, and has no user-define copy operator and no user-defined destructor. Similarly a POD-union is an aggregate union that has no non-static data members of type non-POD-struct, non-POD-union (or array of such types) or reference, and has no user-define copy operator and no user-defined destructor. 8.5.1(1): "An aggregate is an array or class (clause 9) with no user-declared constructors (12.1), no private or protected non-static data members (clause 11), no base classes (clause 10) and no virtual functions (10.3)."