Dimensional Data

C++ is a wonderful programming language with its object-oriented programming features, such as Classes, Objects, constructors, move constructors, copy constructors, destructors, etc. Since the C++11 standards, in modern C++, one of the features is the move constructor that allows you to move the resources from one object to another object without copying them. One of the move constructors is the Trivial Move Constructor which is defined or defaulted in a base class, and in this post, we explain what is a trivial move constructor in Modern C++. First, let’s remember what are the classes and objects in C++. What are classes and objects in modern C++? Classes are defined in C++ using the keyword class followed by the name of the class. Classes are the blueprint for the objects. They are user-defined data types that we can use in our program, and they work as an object constructor. Objects are an instantiation of a class. In C++ programming, most of the commands are associated with classes and objects, along with their attributes and methods. Here is a simple class example below.   class Tmyclass {           public:       std::string str; };   Then we can create our objects with this Type of myclass as below. Now, lets see what is move constructor,. What is a move constructor in modern C++? The move constructor is a constructor that allows you to move the resources from one object to another object without copying them. In other words, the move constructor allows you to move the resources from an rvalue object into an lvalue object. The move constructor is used to move data of one object to the new one, it effectively makes a new pointer to the members of an old object and transfers the resources to the heap memory. When you move a member, if the data member is a pointer, you should also set the value of the member of the old object to a NULL value. When you use the move constructor, you don’t use unnecessary data copying in the memory. This allows you to create objects faster. Mostly, if your class/object has a move constructor, you can use other move methods of other features of C++, for example, std::vector, std::array, std::map, etc. For example, you can create a vector with your class type then you can use the push_back() method that runs your move constructor. Here is the most common syntax for the move constructor in C++ (since C++11).   class_name ( class_name && )   This general syntax is also a syntax for the “Typical declaration of a move constructor” as in below.   class_name ( class_name && ) // Declaration { // Definition } // Definition   What is a trivial move constructor in modern C++? The Trivial Move Constructor is a Move Constructor which is implicitly defined or defaulted and has no virtual member functions, no base classes. The trivial move constructor generally a constructor that comes from template class or base class. The move constructor selected for every direct base of T or for every non-static class type (including array of class type) of T is trivial move constructor. The move constructor for class T is trivial if all of these below are provided. it is implicitly defined or defaulted (not user-provided) it has no virtual member functions it has no virtual base classes and the […]

The Move Constructor is one of the great features of Object Oriented Programming in C++, such as other features like; copy assignment operator constructors, copy constructors, move assignment operators, destructors, etc. Since the C++11 standards, in modern development, the move constructor allows you to move the resources from one object to another object without copying them. One of the move constructors is the Implicitly-defined Move Constructor which is defined or defaulted in a base class, and in this post, we explain What is Implicitly-defined Move Constructor in Modern C++. First, let’s remember what are the classes and objects in C++. What are classes and objects in modern C++? Classes are defined in C++ using the keyword class followed by the name of the class. Classes are the blueprint for the objects. They are user-defined data types that we can use in our program, and they work as an object constructor. Objects are an instantiation of a class. In C++ programming, most of the commands are associated with classes and objects, along with their attributes and methods. Here is a simple class example below.   class Tmyclass {           public:       std::string str; };   Then we can create our objects with this Type of myclass as below. Now, lets see what is move constructor, What is a move constructor in modern C++? The move constructor is a constructor that allows you to move the resources from one object to another object without copying them. In other words, the move constructor allows you to move the resources from an rvalue object into an lvalue object. The move constructor is used to move data of one object to the new one, it effectively makes a new pointer to the members of an old object and transfers the resources to the heap memory. When you move a member, if the data member is a pointer, you should also set the value of the member of the old object to a NULL value. When you use the move constructor, you don’t use unnecessary data copying in the memory. This allows you to create objects faster. Mostly, if your class/object has a move constructor, you can use other move methods of other features of C++, for example, std::vector, std::array, std::map, etc. For example, you can create a vector with your class type then you can use the push_back() method that runs your move constructor. Here is the most common syntax for the move constructor in C++ (since C++11).   class_name ( class_name && )   This general syntax is also a syntax for the “Typical declaration of a move constructor” as shown below.   class_name ( class_name && ) // Declaration { // Definition } // Definition   What is an implicitly-defined move constructor in modern C++? The Implicitly-defined Move Constructor is a Move Constructor which is implicitly defined by another base, or it is an implicitly-declared move constructor neither deleted nor trivial. The Implicitly-defined Move Constructor is defined, which means it has a function body with { } that is generated and compiled by the compiler implicitly. The implicitly-defined move constructor performs full move operations on its members if it is a class or struct type. The implicitly-defined move constructor copies the object representation (as in std::memmove) if it is a union type. According to this paper by Bjarne Stroustrup, By default, an aggregate of elements has an implicitly defined […]

In C++, classes and structs are one of the most important parts of modern app development. In modern C++, there are some rules to support the principles of programming, one of which is the Rule of Five in C++ (also known as the Rule of Six, including constructor). In this post, we explain What is the Rule of Five in C++ with examples. C++ is an Object-Oriented Programming (OOP) language. OOP is a way to integrate with objects which can contain data in the form of attributes or properties of objects, and code blocks in the form of procedures such as methods and functions of objects. Most developers find that using OOP techniques help them to map real-world behavior and bring an organizational structure to data. These attributes and methods are variables and functions that belong to the class – part of the class’s code and they are generally referred to as class members. First, let’s refresh our memory about the fact that Resource Acquisition Is Initialization (RAII) in OOP programming, and the Single Responsibility Principle and how that relates to the Rule of Zero in C++. What is resource acquisition in C++? The principle of Resource Acquisition Is Initialization (RAII) term used in several OOP programming languages, which relates to the ability to manage resources, such as memory, through the copy and move constructors, destruction, and assignment operators. RAII is about the declaration and use of destructors, copy-move operators, and memory management in these members and methods. These cause new rules in development. What is the single responsibility principle in C++? The Single Responsibility Principle (SRP) is a computer programming principle that states “A module should be responsible to one, and only one, actor.” This principle exposes a rule for the classes in C++, called Rule of Zero. Now, let’s see what the Rule of Zero in C++ is. What is the rule of zero in C++? The Rule of Zero means that, if all members have default member functions, no further work is needed. This is the simplest and cleanest semantics of programming. The compiler provides default implementations for all of the default member functions if there are no special member functions that are user-defined. You should prefer the case where no special member functions need to be defined.  Here is more about Rule of Zero with C++ Examples, What is the rule of three in C++? The Rule of Three states that if you need to define a class that has any of the following special member functions a copy constructor, copy assignment operator, or destructor then usually you need to define all these three special member functions. So, these 3 special member functions below should be defined if you have at least one of them defined, Copy constructor Copy assignment operator Destructor Here is more about Rule of Three with C++ examples. What is the rule of five in C++? The Rule of Three is outdated after C++11. C++11 comes with two additional special members of move semantics: the move constructor and the move assignment operator. So, there is another rule, the Rule of Five. The Rule of Five states that if you need to define any of the five special members below, copy constructor, copy assignment operator, move constructor, move assignment operator, or a destructor then you probably need to define or delete (or at least consider) all five of them. Actually, this could be called “The Rule of Six“, because the default constructor should be also declared if there is […]