Do Built-in C Types Have Default Constructors?

Do Built-in Types Possess Default Constructors?

The notion that primitive types in C lack constructors has been a subject of debate. The argument stems from a flawed understanding of the term "default constructor" and the behavior of built-in types.

Default Constructors vs. Value Initialization

Default constructors are member functions that initialize an object's member variables when no other initialization method is specified. Intriguingly, built-in types exhibit similar behavior, leading some to assume the existence of default constructors. However, this assumption is incorrect.

Built-in Types: Absence of Constructors

Primitive types do not have explicit constructors in the traditional sense. Instead, they undergo value initialization, a process that assigns them a default value (e.g., zero for int). This process is not a constructor call; rather, it's a language-defined operation.

Syntax and Behavior: Mimicking Constructors

The introduction of uniform initialization syntax in C 11 introduced the ability to initialize primitive types using the syntax typically used for constructors (e.g., int x{5}). This syntax creates the illusion of constructor usage, but it's still value initialization.

Bjarne Stroustrup's Clarification

Bjarne Stroustrup, the creator of C , acknowledges this conceptual blurring. He suggests that built-in types "are considered to have constructors" due to their constructor-like behavior.

Conclusion

In conclusion, built-in types do not possess default constructors in the traditional sense. Their initialization process, known as value initialization, is a separate process that mimics the behavior of constructors. The uniform initialization syntax introduced in C 11 further obscures this distinction, leading some to mistakenly attribute the behavior of built-in types to the presence of default constructors.

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