Answering to your question about standard I can cite the C++ Standard ยง8.3.2/4: There shall be no references to references, no arrays of references, and no pointers to references. That’s because references are not objects and doesn’t occupy the memory so doesn’t have the address. You can think of them as the aliases to the … Read more
If you want performance, pass by value if you are storing it. Suppose you have a function called “run this in the UI thread”. std::future<void> run_in_ui_thread( std::function<void()> ) which runs some code in the “ui” thread, then signals the future when done. (Useful in UI frameworks where the UI thread is where you are supposed … Read more
Call it like this: foo(*ob); Note that there is no casting going on here, as suggested in your question title. All we have done is de-referenced the pointer to the object which we then pass to the function.
Behavior There is no semantic difference between const T& and T const&; the language treats them as the same type. (The same thing applies to const T* and T const*.) As a matter of style Regarding which you should prefer stylistically, however, I’ll dissent from a lot of the other answers and prefer const T& … Read more
I don’t want to return a copied value because it’s inefficient Prove it. Look up RVO and NRVO, and in C++0x move-semantics. In most cases in C++03, an out parameter is just a good way to make your code ugly, and in C++0x you’d actually be hurting yourself by using an out parameter. Just write … Read more
The reference to the string is passed by value. There’s a big difference between passing a reference by value and passing an object by reference. It’s unfortunate that the word “reference” is used in both cases. If you do pass the string reference by reference, it will work as you expect: using System; class Test … Read more
You cannot pass anything by value in Python. If you want to make a copy of a, you can do so explicitly, as described in the official Python FAQ: b = a[:]
When the language was first evolving, in early releases with real users, there were no references, only pointers. References were added when operator overloading was added, as it requires references to work consistently. One of the uses of this is for an object to get a pointer to itself. If it was a reference, we’d … Read more
Java provides two different types/classes of Reference Objects: strong and weak. Weak Reference Objects can be further divided into soft and phantom. Strong Weak soft phantom Let’s go point by point. Strong Reference Object StringBuilder builder = new StringBuilder(); This is the default type/class of Reference Object, if not differently specified: builder is a strong … Read more
Expressions don’t have return types, they have a type and – as it’s known in the latest C++ standard – a value category. A conditional expression can be an lvalue or an rvalue. This is its value category. (This is somewhat of a simplification, in C++11 we have lvalues, xvalues and prvalues.) In very broad … Read more