Thread: Problems with vectors of objects!

I am currently programming a digital circuit simulator program (uni coursework) ...I have created a vector of objects...

vector <LogicGate*> theCircuit;

Inside logic gate there are functions for all logic gates! ...then there are seperate sub-classes that are derrived from class LogicGate to over-ride some functions to give the ability to create different types of logic; and, or, xor, not. My vector can contain any of these classes, this works fine...

Code:

int Circuit::addGate(int inType){
	switch(inType){
	  case 0 : theCircuit.push_back(new InputGate(newID(), 0)); return 0;
	  case 1 : theCircuit.push_back(new InputGate(newID(), 1)); return 0;
	  case 2 : theCircuit.push_back(new AndGate(newID(), 2));   return 0;
	  case 3 : theCircuit.push_back(new OrGate(newID(), 3));    return 0;
	  case 4 : theCircuit.push_back(new XorGate(newID(), 4));   return 0;
	  case 5 : theCircuit.push_back(new NotGate(newID(), 5));   return 0;
	  default : return -1;
	}
}
// NOTE: newID() is a small function that generates (and then returns) unique id codes.
// To give you an idea what the values are for constructing logic gates; the constructor for the andgate class...

// AndGate::AndGate(int inID, int inType){ .. sets id and logic gate type here .. }

So now i have my vector with the above logic gate objects inserted! ...I thought therefore, that i could easily do the following...

Code:

for (int i=0; i<theCircuit.size(); i++){
  // is current gate an input gate?
  if (theCircuit.at(i).getType() != 0) { ...some code here... }
}

with getType() function being declared in class LogicGate...

Code:

class LogicGate{
private:
    int gateType; // The type of logic gate
    int gateID;   // The ID for the logic gate
    int pID1;     // The first parent for the logic gate
    int pID2;     // The second parent for the logic gate
    int input1;   // The first input value for the logic gate
    int input2;   // The second input value for the logic gate
    int output;   // The output value for the logic gate
public:
  // Class Methods:
  void setID(int);		   // sets the gate ID number
  int getType();			   // returns the gate type code
  void setType(int);		   // sets the gate type code
  int getID();               // returns gates ID
  int getPID1();             // returns gates first parent ID
  int getPID2();             // returns gates second parent ID
  void setPID1(int);         // sets ID of gates first parent
  void setPID2(int);         // sets ID of gates second parent
  void setInput1(int);       // sets gates first input value
  void setInput2(int);       // sets gates second input value
  int getInput1();           // returns value of first input
  int getInput2();           // returns value of second input
  // Virtual Methods:
  virtual int getOutput();   // returns gates output value 
};

However; at compilation i get the error...

Code:

:\WORK\CIRCUIT.CPP(100) : error C2228: left of '.getType' must have class/struct/union type

Its confusing, because to me it appears that this should work fine!!! ...I tried a simpler version using vectors of objects and that worked fine, i could access all the objects functions using the vector.at(x).functionName() with no problems at all!!! so what is going on here??? ...anyone know what i am doing wrong???

Cheers!!! Matt..