C Constructor Delegation: Why Initialize in the Member Initializer List?

Delegating Constructors: A Deeper Dive

Constructor delegation in C is a technique that allows a constructor to call another constructor of the same class. It is useful for reducing code duplication when multiple constructors perform similar operations.

In the provided example, the aim is to delegate the construction of a Bitmap object using a different argument type (e.g., HBITMAP or WORD ResourceID). The second approach presented in the question correctly demonstrates constructor delegation in the initialization list:

Bitmap::Bitmap(WORD ResourceID) : Bitmap((HBITMAP)LoadImage(...)

This syntax initializes the Bitmap object using the HBITMAP constructor and passes the loaded resource as the argument. This is preferred over the first approach, which would create a temporary HBITMAP object and then attempt to delegate to the HBITMAP constructor.

Constructor delegation can only be done within the initialization list of the constructor. If you attempt to delegate from the constructor body, as in the first approach, it will lead to errors or unintended behavior.

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