What are the best practices for using const in C++?

What are the best practices for using const in C++?

Using const in C++ helps to enforce immutability, making your code safer and easier to understand. Here are some best practices:

1. Use const for function parameters when the function does not modify the argument.
2. Use const member functions to indicate that the function does not modify the object.
3. Prefer const references for passing large objects to avoid unnecessary copies.

Can you give an example of using const with function parameters?

Sure! Here's an example:

void printValue(const int value) {
    std::cout << value << std::endl;
}

In this case, value cannot be modified inside the function, ensuring that the original argument remains unchanged.

What about using const with pointers?

When using pointers, you can have a pointer to a const value or a const pointer. For example:

const int* ptr = &value; // Pointer to a const int
int* const ptr2 = &value; // Const pointer to an int

The first means you can't change the value pointed to, while the second means you can't change the pointer itself.

Are there any downsides to using const?

While using const is generally beneficial, it can sometimes lead to more complex code, especially when dealing with const-correctness in inheritance or when using templates. However, the benefits of clarity and safety usually outweigh these downsides.