What are the differences between passing a parameter by reference and by constant reference?

when you use use ‘normal’ parameter, you pass the parameter by value and hence creating a copy of the parameter you pass. if you are using const reference, you pass it by reference and the original data is not copied. in both cases, the original data cannot be modified from inside the function.

Should we pass a Shared_ptr by reference or by value?

Most of the time passing shared_ptr by reference, and even better by const reference, would do. An example of when passing shared_ptr by value is really necessary is when the caller passes a shared object to an asynchronous callee – ie the caller goes out of scope before the callee completes its job.

What does const Shared_ptr mean?

boost::shared_ptr prevents modification of the Bar object through the shared pointer. As a return value, the const in boost::shared_ptr const means that you cannot call a non-const function on the returned temporary; if it were for a real pointer (e.g. Bar* const ), it would be completely ignored.

Should be passed by const reference?

When passing an argument by reference, always use a const reference unless you need to change the value of the argument. Non-const references cannot bind to r-values. A function with a non-const reference parameter cannot be called with literals or temporaries.

What is the difference between pass by value and pass by reference in Java?

Basically, pass-by-value means that the actual value of the variable is passed and pass-by-reference means the memory location is passed where the value of the variable is stored.

When should you use Shared_ptr?

Use shared_ptr if you want to share ownership of a resource. Many shared_ptr can point to a single resource. shared_ptr maintains reference count for this propose. when all shared_ptr’s pointing to resource goes out of scope the resource is destroyed.

Can a Shared_ptr be null?

A shared_ptr that points to no object is called a null shared_ptr and shall not be dereferenced. Notice though that an empty shared_ptr is not necessarily a null shared_ptr, and a null shared_ptr is not necessarily an empty shared_ptr.”

Does passing by reference save memory?

When an object (or built-in type) is passed by reference to a function, the underlying object is not copied. The function is given the memory address of the object itself. This saves both memory and CPU cycles as no new memory is allocated and no (expensive) copy constructors are being called.

What is the difference between passing by value and passing by reference in Java?

Object variables in Java always point to the real object in the memory heap. A mutable object’s value can be changed when it is passed to a method. “Passing by value” refers to passing a copy of the value. “Passing by reference” refers to passing the real reference of the variable in memory.