hash table error on insert

//Ennio Bozzetti
//Hash.h
 
#ifndef HASH_H
#define HASH_H
 
#include <iostream>
#include <string>
#include <stdlib.h>
#include "student.h"
 
class hash{
	public:
		hash();
		hash(int newsize);
		~hash();
		void insert(student * newstudent);
	private:
		int size;
		student * myArray;
		int * used;
};
#endif
 
 
//ENnio Bozzetti
//hash.cpp
 
#include "hash.h"
#include <stdlib.h>
 
hash::hash(){
 
}
hash::hash(int newsize){
	size = newsize;
	myArray = new student[size];
	used = new int[size];
}
 
hash::~hash(){
	delete [] myArray;
	delete [] used;
}
 
void hash::insert(student * newstudent){
	int key = atoi(newstudent->getStudentLName().c_str()) % size;
	int counter=0;
	int done = 0;
	while(counter < size && !done){
		if(used[key] == 0){
			myArray[key] = newstudent;
			used[key] = 1;
			done = 1;
		} else {
			key = (key + 1) % size;
			counter++;
		}
	}
}
 
 
 
 
*************************
Student.h
 
/*
file name: student.h
date: 01/30/2007
student id: s0547650
Class: CS 503
Description: Student header file
*/
#ifndef STUDENT_H
#define STUDENT_H
 
#include <string>
using namespace std;
class student {
 
	public: //Function members
		student(); //Constructor
		student(string sId, string sFName, string sLName, string sMName, string sHometown, string sState, string sPhone, string sGender, int sYear, int sCredits, double sGpa, string sMajor);
		string getStudentID() const;
		string getStudentFName() const;
		string getStudentLName() const;
		string getStudentMName() const;
		string getStudentHometown() const;
		string getStudentState() const;
		string getStudentPhone() const;
		string getStudentGender() const;
		int getStudentYear() const;
		int getStudentCredits() const;
		double getStudentGpa() const;
		string getStudentMajor() const;
		void setStudentID(string ID);
		void setStudentFname(string fName);
		void setStudentLname(string lName);
		void setStudentMname(string mName);
		void setStudentHometown(string homeTown);
		void setStudentState(string state);
		void setStudentPhone(string phone);
		void setStudentGender(string gender);
		void setStudentYear(int year);
		void setGpa(double nGpa);
		void setMajor(string nMajor);
		void setCredit(int nCredit);
		void show();
 
	private: //Data members
		string studentId;
		string studentFName;
		string studentLName;
		string studentMName;
		string studentHometown;
		string studentState;
		string studentPhone;
		string studentGender;
		int studentYear;
		int studentCredits;
		double studentGpa;
		string studentMajor;
};
#endif