What is operator overloading in C++?

Operator overloading in C++ allows programmers to redefine how standard operators, such as +, -, *, and others, work when applied to objects of user-defined types (classes or structs). By overloading an operator, you enable custom behaviors that correspond to the operations of those objects, which makes the code more intuitive and easier to read.

For instance, if you are working with a class that represents complex numbers, you could overload the '+' operator to enable the addition of two complex numbers in a natural way, similar to how you would add two integers. This customization can enhance the functionality of user-defined types and make it possible to use them seamlessly in expressions alongside built-in types.

The other options do not accurately describe operator overloading. Rewriting functions in multiple files involves aspects of code organization and modular programming, not operator behavior. Creating new data types refers to defining classes or structs, not specifically to operator behavior. Optimizing existing operators could involve performance improvements but does not pertain to redefining their workings for custom data types. Thus, the essence of operator overloading lies in providing tailored behavior for operators in context with user-defined types.