C++11 pod type (Learn)

What is the pod type? Pod Full name plain old Data. In layman's words, a class or struct can keep its data intact after a binary copy, so it is a pod type. An ordinary definition1. There are trivial constructors2. There are trivial copy constructors3. There are trivial move constructors4. There is a trivial copy assignment operator5. There is a trivial move assignment operator6. There are trivial destructors7. Cannot contain virtual functions8. cannot contain virtual base class [CPP] View plaincopy on code to view the snippet derivation to my Code slice # include"StdAfx.h"#include <iostream>UsingNamespaceStdClassA {a () {}};Class B {B (b&){} };Class C {C (c&&){} };Class D {DOperator= (d&){} };Class E {EOperator= (e&&){} };Class F {~F () {}};Class G {Virtualvoid foo () =0; };Classh:g {};ClassI {};int _tmain (int argc, _tchar*Argv[]) {std::cout << std::is_trivial<a>::value << Std::endl;//There are extraordinary constructors std::cout << Std::is_trivial<b>::value << Std::endl;//There are extraordinary copy constructors Std::cout << std::is_trivial<c>::value << Std::endl;//There is an extraordinary copy assignment operator Std::cout << std::is_trivial<d>::value << Std::endl;//There is an extraordinary copy assignment operator Std::cout << std::is_trivial<e>::value << Std::endl;//There is an extraordinary move assignment operator Std::cout << std::is_trivial<f>::value << Std::endl;//There are extraordinary destructors std::cout << std::is_trivial<g>::value << Std::endl;//There are virtual functions std::cout << std::is_trivial//There are virtual base classesStd::cout << std::is_trivial<i>::value << Std::endl;//The Ordinary classSystem"Pause");Return0; The definition of the run result standard layout1All non-static members have the same access rights2There can be at most one class in the inheritance tree with non-static data members3The first non-static member of a subclass cannot be a base class type4. no virtual function5. No virtual base class6All non-static members conform to the standard layout type [CPP] view plaincopy on code to view the snippet derivation to my Code slice # include"StdAfx.h"#include <iostream>UsingNamespaceStdClassAPrivate:IntAPublic:Intb };ClassB1 {StaticIntX1; };ClassB2 {IntX2; };ClassB:B1, B2 {IntX };ClassC1 {};ClassC:C1 {C1 C;};Class D {Virtualvoid foo () =0; };Classe:d {};ClassF {A x;};int _tmain (int argc, _tchar*Argv[]) {std::cout << std::is_standard_layout<a>::value << Std::endl;//violation of definition 1. Members A and B have different access rights std::cout << Std::is_standard_layout<b>::value << Std::endl;//violation of definition 2. The inheritance tree has more than two classes (including) with non-static members std::cout << std::is_standard_layout<c>::value << Std::endl;//Violation of definition 3. The first non-static member is the base class type Std::cout << std::is_standard_layout<d>::value << Std::endl;//violation of definition 4. There are virtual functions std::cout << std::is_standard_layout<e>::value << Std::endl;//violation of definition 5. There are virtual base classes std::cout << std::is_standard_layout<f>::value << Std::endl;//Violation of definition 6. Non-static member x does not conform to the standard layout typeSystem"Pause");Return0; The use of the run results pod when a data type satisfies "trivial definition" and "standard Layout", we think of it as a pod data. You can use Std::is_pod to determine whether a type is a pod type. As stated at the beginning of the article, a pod type can be binary copy, take a look at the following example. [CPP] View plaincopy on code to see a snippet derived from my Code slice # include"StdAfx.h"#include <iostream>#include <Windows.h>UsingNamespaceStdClassAPublic:IntXDoubleY };int _tmain (int argc, _tchar*Argv[]) {if (std::is_pod<a>:: Value) {Std::cout <<"Before"<<Std::endl; A; a.x =8; A.Y =10.5 Std::cout << a.x << Std::endl; std::cout << a.y << Std::endl; size_t size = sizeof< Span style= "color: #000000;" > (a); char *p = new char[size]; memcpy (p, &a, size); A *pa = (a*) p; std::cout <<  "after "<< Std::endl; Std::cout << pa->x << Std::endl; std::cout << pa->y << std: : Endl; Delete p; } system ("Pause"); return 0; The results of the operation can be seen, after a binary copy of a pod type, the data is migrated successfully. 

C++11 pod type (learn)