C++ overloading of << or >> example and explanation -

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• what basic rules , idioms operator overloading? 7 answers

i learning c++ , don't understand how << , >> operator overloading works.

can please provide example and/or explanation of method overloads either operator?

class {     int x;     public:     a(int _x) : x(_x){}     friend ostream& operator<<(ostream& os, elem); };  ostream& operator<<(ostream& os, elem) {     os << elem.x;     return os; } 

then can call

std::cout << a(5); //prints 5 

explanation: you're doing in here, making friend function class. we're making friend because want refer private fields. if have struct, don't have declare friend.

we're returning ostream& can "chaining" - cout << x << y wouldn't work if returned ostream. we're taking reference os same reason, plus want actual stream(otherwise you'd end writing copy). , we're taking elem a, because it's going printed. then, print os whatever want - remember, can print elements ostream can print(e.g. ints, strings, etc.). print os, , return it(chaining). remember, calling cout<<x equivalent calling operator<<(cout, x)

ps. answered specific << operator overloading, because that's first came mind, , thought you're struggling with. didn't make clear whether want overload operator ostream, or class, can use function.