when i have a class , where i need objects of, and i want them all to have a CONSTANT id number, that is to be set in a loop in main? is this possible in some way?
? like i tested it, it did not work, wich is logical cause u cant modify constant objects. but is their some way to make these unique constant id numbers in a loop? in main? or do i realy need to write 100 difrent classes with a difrent const id number?Code:for (int x = 0; x<100; x++) { class.setid (x); }
You could use a static integer member which increments by 1 each time a new object is createdBefore the program reaches main(), id_numbers is created, and initialised to zero.Code:#include <iostream> class MyClass { static int id_numbers; const int object_id; public: MyClass() : object_id(id_numbers) { ++id_numbers; } int id() const; }; int MyClass::id_numbers = 0; int MyClass::id() const { return object_id; } int main() { MyClass obj1; MyClass obj2; MyClass obj3; std::cout << "Object 1 - ID: " << obj1.id() << std::endl; std::cout << "Object 2 - ID: " << obj2.id() << std::endl; std::cout << "Object 3 - ID: " << obj3.id() << std::endl; }
Every time a new object is created, the constructor automatically assigns the const object_id member with the value of id_numbers and then increments id_numbers ready for the next constructor call.
Last edited by Bench82; 12-28-2006 at 06:03 PM.
You have to initialize a constant data member with a member initializer:
Code:class C { const int id; public: C(int id) : id(id) {} };
[QUOTE=Bench82]You could use a static integer member which increments by 1 each time a new object is created [CODE]#include <iostream>
man, your a genius, why didnt i think of that! thnx man
