Understanding the "functions that differ only by return type can’t be overloaded" Error in C+ +

Learn why you receive the "functions that differ only by return type can't be overloaded" error in C+ + , and discover how to properly structure your classes and functions in your code.
---
This video is based on the question https://stackoverflow.com/q/71451996/ asked by the user 'K. A. Kusakov' ( https://stackoverflow.com/u/18195488/ ) and on the answer https://stackoverflow.com/a/71452190/ provided by the user 'Jerry Coffin' ( https://stackoverflow.com/u/179910/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Why do I get "functions that differ only by return type cant't be overloaded" error when nothing is really overloaded?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/licensing
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding the "functions that differ only by return type can’t be overloaded" Error in C+ +

C+ + can sometimes be tricky, especially when it comes to managing classes and functions. One error that developers often encounter is the message stating that "functions that differ only by return type can’t be overloaded." If you’ve ever faced this error, rest assured it’s a common hurdle, often caused by the order in which classes and functions are defined in your code.

The Problem: A Case Study

Let’s dig into an example to understand this error better. Consider the following C+ + code snippet:

[[See Video to Reveal this Text or Code Snippet]]

When you attempt to compile this code, you’ll encounter the compiler error message stating "functions that differ only by return type can’t be overloaded." You might wonder: But why do I see this error when there is no other definition for get_employee() anywhere in my code?

The Explanation: Function Declaration Order

The root of the issue lies in the order of declarations in your code. In C+ + , the compiler processes code from top to bottom. When you defined the function get_employee(), you attempted to use the type employee before the employee class was actually defined. This is a big no-no in C+ + .

Fixing the Problem

To resolve this issue, you need to move the definition of the employee class before the implementation of the get_employee() function. Here’s the corrected version of your code:

[[See Video to Reveal this Text or Code Snippet]]

Now, the employee class is fully defined before it's utilized in the function get_employee(), and the compiler can understand what employee is when it compiles the function.

Why the Confusing Error Message?

You might still be wondering why the compiler throws that specific error message. The confusion stems from how the compiler handles undefined types.

Initially, when get_employee() is defined, the compiler does not recognize employee as a valid type.

In C+ + , when a function is declared with an undefined type, the compiler defaults to assuming that it returns int if no return type is specified.

When the actual definition comes in, the compiler thinks you've potentially defined a new overload of get_employee() that differs only by return type, leading it to issue the confusing error message.

Conclusion

In summary, the "functions that differ only by return type can’t be overloaded" error in C+ + is typically the result of improper ordering of class and function definitions. Ensuring that your classes are defined before you utilize them in functions is crucial to prevent such errors.

Key Takeaways

Order Matters: Always define your classes before referencing them in functions.

Compiler Behavior: Understand how the compiler treats undefined types and return values to anticipate potential error messages.

By following these guidelines, you can clarify your code's structure and avoid confusing error messages, making your programming experience in C+ + smoother and more productive.

Видео Understanding the "functions that differ only by return type can’t be overloaded" Error in C+ + канала vlogize