Скачать или смотреть How to Call a Specific Function from an Array of Functions in Arduino/C+ +

Learn how to efficiently call specific functions using an array of function pointers in Arduino/C+ + . This post offers a clear solution to a common problem faced by developers.
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How to Call a Specific Function from an Array of Functions in Arduino/C+ +

In the world of programming, especially when working with Arduino and C+ + , managing multiple modes or states can be quite a challenge. A common scenario is the need to switch between different functions using a simple button press. Many developers initially turn to long if-else statements, but there's a more elegant and efficient solution: using an array of function pointers.

The Problem: Managing Modes Efficiently

Let’s consider a situation where you are developing a watch based on Arduino/ATMega. For switching between different modes, you might have initially written extensive conditional statements, such as:

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While this approach works, it becomes cumbersome and difficult to manage. In the quest for an optimized solution, you tried to implement an array of functions and call them based on an index variable. However, when you attempted to compile your code, you faced an error indicating that "expression cannot be used as a function."

The question then arises: How do you correctly call a function from an array of functions in C+ + ?

The Solution: Using Function Pointers

To fix the error, the essential step is to recognize that you're trying to use an array of pointers to functions rather than an array of integers. In C+ + , the type of the array needs to be defined correctly to point to functions.

Step 1: Define Function Pointers

Instead of declaring your function array as integers, declare it as an array of function pointers. Here’s how you can do this:

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Step 2: Understanding Function Signatures

In the above line, the syntax void (*)() specifies that Modes is an array of pointers to functions that do not take any arguments and return nothing (void). This is key because it explicitly tells the compiler what type of functions will be in the array.

Step 3: Optional: Using Type Definitions for Clarity

To enhance the readability of your code, you can use a typedef to define the function pointer type:

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Using this typedef not only simplifies your array declaration but also makes your code more maintainable and understandable.

Complete Example Code

Here’s how a simplified version of your Arduino code might look:

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Conclusion

By correctly utilizing an array of function pointers, you can streamline mode management in your Arduino project significantly. This method not only makes your code cleaner but also enhances its efficiency. If you encounter the "expression cannot be used as a function" error, remember to revisit your function type definitions and ensure they align with your implementation. Happy coding!