Error in class constructor

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Error in class constructor

 
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  #1
May 17th, 2006
Hi to all! I'm writing a simple simulation program for elevators but i get a problem, namely:

C++ Syntax (Toggle Plain Text) 
  1.  
  2. elevator.cpp: In constructor `Elevator::Elevator(int)':
  3. elevator.cpp:41: error: no matching function for call to `Button::Button()'
  4. elevator.cpp:10: note: candidates are: Button::Button(const Button&)
  5. elevator.cpp:16: note:                 Button::Button(int, bool)
  6. elevator.cpp:41: error: no matching function for call to `Button::Button()'
  7. elevator.cpp:10: note: candidates are: Button::Button(const Button&)
  8. elevator.cpp:16: note:                 Button::Button(int, bool)
  9. elevator.cpp:44: error: `Buttonset' undeclared (first use this function)
  10. elevator.cpp:44: error: (Each undeclared identifier is reported only once for each function it appears in.)
  11. elevator.cpp:45: error: no match for 'operator=' in '((Elevator*)this)->Elevator::Alert = (((Button*)operator new(8u)), (<anonymous>->Button::Button(3, 0), <anonymous>))'
  12. elevator.cpp:10: note: candidates are: Button& Button::operator=(const Button&)

The code that produces this minor irritation is the constructor of the 2nd class:

C++ Syntax (Toggle Plain Text) 
  1.  
  2. class Button {
  3.       private: 
  4.                enum Types {inside, outside, alarm};
  5.                Types type;
  6.                bool active;
  7.       public:
  8.                Button(int typ, bool state) {
  9.                       if (typ!=1 && typ!=2 && typ!=3)
  10.                                  throw ("Crappy button type in initialisation...Terminating.");
  11.                       if(state!=0 && state!=1)
  12.                                   throw("Boolean expected in button class initialisation... Terminating.");
  13.                       type = Types(typ-1);
  14.                       active = state;
  15.                }
  16.  
  17.                inline bool is_active(void) { return active; };
  18.                inline int  who(void) { return type; };
  19.                inline void flashb(void) { active=!active; };
  20.                inline void press(void) { active = 1; };
  21. };
  22. class Elevator {
  23.       private:
  24.               int number;
  25.               Button ButtonSet[10];
  26.               Button Alert;
  27.               queue<int> queue;
  28.               int last_stop;
  29.               enum Status { moving, idle, alert };
  30.               Status stats;
  31.       public:
  32.              Elevator(int num) {
  33.                           number = num;
  34.                           for(int i=0; i<10; i++)
  35.                                   Buttonset[i] = new Button(1, 0);
  36.                           Alert = new Button(3, 0);
  37.                           stats = Status(1);
  38.              };
  39.              void pressb (int num);
  40.              void emergency(void);
  41.              inline void set_stats(int status) { stats = Status(status-1); } ;
  42.              inline int  get_stats(void) { return (int)stats; };
  43.              int move(void);
  44. };

I would be thankful if somebody shares an idea of the possible error!
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Re: Error in class constructor

 
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  #2
May 17th, 2006
You don't have a default constructor for Button.

Also:
C++ Syntax (Toggle Plain Text) 
  1. ButtonSet[i] = new Button(1, 0);
You need a pointer with new.
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Re: Error in class constructor

 
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  #3
May 17th, 2006
You're trying to create objects of type Button, but don't have the constructors to match. Remember that if you provide your own constructor within a class, then you do not get a default constructor.

You also seem to have other problems - you can't assign an int to an object of an enumerated type. eg,
C++ Syntax (Toggle Plain Text) 
  1. stats = Status(1);
this needs to be
C++ Syntax (Toggle Plain Text) 
  1. stats = idle;
¿umop apisdn upside down?
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Re: Error in class constructor

 
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  #4
May 17th, 2006
Default constructor i don't need in this case, because i need to set up some predifined values for buttons and states. I'm still a bit confused how to edit my code so it's working, though. As for the
C++ Syntax (Toggle Plain Text) 
  1.  
  2. stats = Status(1);
maybe it's an error but i haven't done any C++ programming in quite a while and also the compiler doesn't recognize it as an error. Until the testing comes a lot of code is to be written but the pebble in the shue is still there..
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Re: Error in class constructor

 
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  #5
May 17th, 2006
Without the default constructor, you can't do this:
C++ Syntax (Toggle Plain Text) 
  1. Button ButtonSet[10];
Perhaps you meant this:
Button *ButtonSet[10];
Button *Alert;

---

Or perhaps this for a default constructor?
Button(int typ = 1, bool state = 0) {
"One of the methods used by statists to destroy capitalism consists in establishing controls that tie a given industry hand and foot, making it unable to solve its problems, then declaring that freedom has failed and stronger controls are necessary." --Ayn Rand
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Re: Error in class constructor

 
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  #6
May 17th, 2006
Perhaps the second :-) Thanks!
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