Explicitly initialize the thread with a reference_wrapper by using std::ref: auto thread1 = std::thread(SimpleThread, std::ref(a)); (or std::cref instead of std::ref, as appropriate). Per notes from cppreference on std:thread: The arguments to the thread function are moved or copied by value. If a reference argument needs to be passed to the thread function, it has to … Read more
f2 is taking it’s arguments by reference, which is essentially an alias for the arguments you pass. The difference between pointer and reference is that a reference cannot be NULL. With the f you need to pass the address (using & operator) of the parameters you’re passing to the pointer, where when you pass by … Read more
There are essentially three kinds of ‘function calls’: Pass by value Pass by reference Pass by object reference Python is a PASS-BY-OBJECT-REFERENCE programming language. Firstly, it is important to understand that a variable, and the value of the variable (the object) are two seperate things. The variable ‘points to’ the object. The variable is not … Read more
I found myself disagreeing with the highest-voted answer, so I went looking for expert opinons and here they are. From http://channel9.msdn.com/Shows/Going+Deep/C-and-Beyond-2011-Scott-Andrei-and-Herb-Ask-Us-Anything Herb Sutter: “when you pass shared_ptrs, copies are expensive” Scott Meyers: “There’s nothing special about shared_ptr when it comes to whether you pass it by value, or pass it by reference. Use exactly the … Read more
In modern browsers, you can use the let or const keywords to create a block-scoped variable: for (let i = 0; i < results.length; i++) { let marker = results[i]; google.maps.event.addListener(marker, ‘click’, () => change_selection(i)); } In older browsers, you need to create a separate scope that saves the variable in its current state by … Read more
You have several choices. The one that makes the most sense really depends on what you’re trying to do. Choice 1: make toyNumber a public member variable in a class class MyToy { public int toyNumber; } then pass a reference to a MyToy to your method. void play(MyToy toy){ System.out.println(“Toy number in play ” … Read more
It doesn’t quite work that way in Python. Python passes references to objects. Inside your function you have an object — You’re free to mutate that object (if possible). However, integers are immutable. One workaround is to pass the integer in a container which can be mutated: def change(x): x[0] = 3 x = [1] … Read more
Types of Things in Swift The rule is: Class instances are reference types (i.e. your reference to a class instance is effectively a pointer) Functions are reference types Everything else is a value type; “everything else” simply means instances of structs and instances of enums, because that’s all there is in Swift. Arrays and strings … Read more
The short answer is, Python always does pass-by-value, but every Python variable is actually a pointer to some object, so sometimes it looks like pass-by-reference. In Python every object is either mutable or non-mutable. e.g., lists, dicts, modules and Pandas data frames are mutable, and ints, strings and tuples are non-mutable. Mutable objects can be … Read more
Initially, it can be represented graphically as follow: Then, the sort is applied myList.Sort(); Finally, when you did: myList’ = myList2, you lost the one of the reference but not the original and the collection stayed sorted. If you use by reference (ref) then myList’ and myList will become the same (only one reference). Note: … Read more