defaultkonstruktor

Defaultkonstruktor is a constructor of a class that can be invoked without supplying arguments. It is used to create objects with a default-initialized or otherwise simple initial state. The availability and behavior of a defaultkonstruktor depend on the programming language and the class definition.

In C++, a defaultkonstruktor means a constructor with no parameters. If no constructors are declared, the compiler implicitly declares a defaultkonstruktor that default-initializes data members and base classes. If any constructor with parameters is declared, the compiler does not generate a defaultkonstruktor unless it is explicitly declared (for example using = default). In-class member initializers can provide default values, reducing the need for an explicit defaultkonstruktor.

In Java and C#, a no-argument constructor is treated similarly to a defaultkonstruktor. In Java, if a class has no constructors at all, the compiler automatically provides a public no-argument constructor. If any constructor is declared, a no-argument constructor is not generated automatically and must be written if needed. In C#, a parameterless constructor is provided if none are defined; once a constructor is declared, another one must be defined explicitly if required.

Practical considerations: Many frameworks and libraries rely on a no-argument constructor for reflection, object-relational mapping, serialization, or deserialization. If only parameterized constructors are provided, an explicit defaultkonstruktor may be necessary. Accessibility also matters: the defaultkonstruktor must be reachable from the code that creates instances.