Defaultconstructed

The term "default-constructed" refers to an object that has been created using the default constructor of a class. In C++, a default constructor is a special member function that is called when an object is instantiated without any arguments. This constructor initializes the object to a valid state, typically by setting member variables to default values.

In C++11 and later, the default constructor can be explicitly defined or implicitly generated by the compiler if no other constructors are provided. If a class has no user-defined constructors, the compiler will automatically generate a default constructor that initializes all member variables to their default values (e.g., zero for integers, null for pointers, and default-constructed for other objects).

Default-constructed objects are often used in scenarios where the initial state of an object is not immediately known or relevant. For example, they can be used in containers like std::vector or std::list, where the objects are created but not yet assigned specific values. They can also be used in algorithms that require temporary objects.

However, it is important to note that not all classes have a default constructor. If a class has a user-defined constructor that requires arguments, it will not have a default constructor unless one is explicitly defined. In such cases, attempting to default-construct an object of that class will result in a compilation error.

In summary, a default-constructed object is one that has been created using the default constructor of a class, initializing it to a valid state with default values. This concept is fundamental in C++ for creating and managing objects efficiently.