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

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

Using const references in C++ is a great way to improve performance and safety. Here are some best practices:

1. Use const references for large objects to avoid unnecessary copying.
2. Prefer const references for function parameters when you don't need to modify the argument.
3. Use const references for return types when returning large objects to avoid copies.

Can you give an example of a function using const references?

Sure! Here's a simple example:

void printVector(const std::vector<int>& vec) {
    for (const int& num : vec) {
        std::cout << num << " ";
    }
}

In this function, vec is passed as a const reference, which avoids copying the entire vector.

Are there any situations where I shouldn't use const references?

Yes, you should avoid using const references when:

1. You need to modify the object.
2. The object is small (like built-in types) where copying is cheaper than referencing.
3. You are dealing with temporary objects that won't outlive the reference.

What about using const references with classes?

Using const references with classes is beneficial, especially for large objects. It allows you to pass objects without copying them, while ensuring that the object cannot be modified within the function. Just ensure that the class has a proper copy constructor and assignment operator if needed.