How to Correctly Pass Parameters in C ?

How to Pass Parameters Correctly

In C , parameter passing techniques are crucial for maintaining object integrity and performance. Below are answers to your questions and best practices for parameter passing:

Best Practices for Parameter Passing

• Modify Original Object: Pass by lvalue reference (e.g., my_class&) if the function modifies the original object.
• Observe Object State: Pass by lvalue reference to const (e.g., my_class const&) if the function only needs to observe the object's state.
• Create Copy: Pass by value (e.g., my_class newObject) if the function requires a copy of the object to work with.

Handling Moves and Copies

In the provided examples, the use of CreditCard&& in the constructor is incorrect. Rvalue references cannot bind to lvalues like cc. To avoid causing errors, consider creating constructor overloads for lvalues and rvalues:

Account(std::string number, float amount, CreditCard const& creditCard)
: number(number), amount(amount), creditCard(creditCard) // Copy for lvalues
{ }

Account(std::string number, float amount, CreditCard&&& creditCard)
: number(number), amount(amount), creditCard(std::move(creditCard)) // Move for rvalues
{ }

Using Perfect Forwarding

For more complex scenarios, std::forward is commonly used for perfect forwarding in templates:

template<typename C>
Account(std::string number, float amount, C&&& creditCard)
: number(number), amount(amount), creditCard(std::forward<C>(creditCard)) 
{ }

This allows the constructor to automatically determine whether to perform a move or copy based on the type deduced for C.

By adhering to these best practices, you can ensure proper parameter passing and avoid performance issues or errors related to unwanted object modification or copying.

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