How Does Overloaded Method Resolution Handle Null Values?

Overloaded Method Resolution and Null Arguments

The process of selecting the correct overloaded method when a null argument is provided follows a specific sequence of steps.

1. Accessibility:

Initially, the compiler filters out any inaccessible overloaded methods based on the calling code's access rights.

2. Applicability:

Next, it identifies applicable methods. A method is considered applicable if each formal parameter has a corresponding argument that can be implicitly converted. Null values cannot be implicitly converted to value types (like int or Point), eliminating those methods from consideration.

3. params Method Handling:

Methods using the params keyword can be invoked either expanded (treating the array as individual arguments) or unexpanded (treating it as a single array argument). If both are applicable, the expanded form is preferred, and the unexpanded version is discarded.

4. Best Match Selection:

Finally, the compiler compares the remaining applicable methods to find the most specific match. A method with a more specialized parameter type is considered more specific than one with a more general type.

In scenarios with ambiguity (multiple equally specific methods), as in the example provided, the compiler cannot determine the best candidate, resulting in a compilation error. The object parameter type is less specific than both object[] and string, leading to this ambiguity.

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