Do Initialization Lists Offer Performance Gains When Initializing Built-in Types in C ?

Efficiency Gains of Initialization Lists: Clarifying the Example

In the realm of C , initialization lists play a pivotal role in optimizing member initialization. While initialization lists offer advantages when initializing non-built-in class members, the question posed investigates whether they yield any performance gains in initializing built-in types.

Initialization List vs. Assignment:

The first version of the code snippet, employing an initialization list, directly constructs the data member name with the value of n. However, the second version first creates a temporary string object with the value n and then assigns it to the name member using the copy-assignment operator.

Efficiency and Initialization Lists:

In the typical case where the expression being assigned to the member variable is identical to its type, initialization lists excel due to their direct construction capabilities. This eliminates the need for creating and destroying a temporary object as in the second version.

Case of Built-In Types:

Applying these principles to the provided example, we observe that the second version calls the string's default constructor to create the temporary object and then assigns it to name using the copy-assignment operator. This introduces additional steps not present in the initialization list approach. Thus, the first version, which directly initializes name with n, is more efficient.

Conclusion:

In summary, using initialization lists provides efficiency advantages not just for non-built-in types but also for built-in types where direct construction is possible. This enhances the performance of class initialization by eliminating unnecessary object creation and destruction.

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