#include<iostream> using namespace std; class MyClass { public: MyClass(int i = 0) { cout << i; } MyClass(const MyClass &x) { cout << 2; } MyClass &operator=(const MyClass &x) { cout << 3; return *this; } ~MyClass() { cout << 4; } }; int main() { MyClass obj1(1), obj2(2); MyClass obj3 = obj1; return 0; }运行时的输出结果是()