Overloading HugeInteger

I am back LOL...  I am trying to overload a previous version of HugeInteger.  All methods worked and such before attempt to overload.  I am gonna go threw this bit by bit.  Since I was suppose to overload every single function in my already completed work, i figured I would start with one I thought I kind of understood.  HA HA what a joke that was.  Here is my attempt at overloading output <<  However I get four different errors.  I have included the .h file and all methods up to the output << method hoping someone can tell me why I am getting these errors.
.h file

class OLHugeInteger
{
      friend ostream &operator<<(ostream &, const OLHugeInteger &);

public:
      OLHugeInteger();      //constructor
      void input();      
      void copyBigNumber(int [], const int []) const ;

      OLHugeInteger add(const OLHugeInteger &) const;
      OLHugeInteger subtract(const OLHugeInteger &) const;
      OLHugeInteger multiply(const OLHugeInteger &) const;
      
      OLHugeInteger multiplySub(int) const;
      OLHugeInteger opposite(const OLHugeInteger &) const;
      

      bool equalTo(const OLHugeInteger &) const;
      bool notEqualTo(const OLHugeInteger &) const;
      bool greaterThan(const OLHugeInteger &) const;
      bool greaterThanOrEqualTo(const OLHugeInteger &) const;
      bool lessThan(const OLHugeInteger &) const;
      bool lessThanOrEqualTo(const OLHugeInteger &) const;
      bool isZero() const;

private:
      int const arraySize;      //const array size
      bool isNegative;      //determines if array of integers is negative
      char line[41];
      int bigNumber[40];      //array to hone users inputted integer
      void copyBigNumber(int [], const int []);      //creates copy of bigNumber[]


};      //End class OLHugeInteger

#endif

.cpp up to output<<
#include <iostream>
using namespace std;
using std::cout;
using std::cin;
using std::endl;

#include <string>      //for string length (strlen)

#include "OLHugeInteger.h"      //include definition of class HugeInteger

int inputSize = 0;      //default size of users integer

//default constructor const arraySize = 40
OLHugeInteger::OLHugeInteger() :arraySize(40)
{
      for (int loopSize = 0; loopSize < arraySize; loopSize++)
            //initialize array with 0's
            bigNumber[loopSize] = 0;      
      
      //set bool isNegative to false
      isNegative = false;

}//end constructor

void OLHugeInteger::input()
{
      //characters read in to hold integer values
    char line[41];      
     
      //ask for usre input and make sure no more than 40 digits where entered
      //if more than 40 digits are entered, drop extra from bigNumber
      cout << "Enter Huge Integer (Max: 40 digits, extra digits will be dropped!): " << endl;
      cin.getline(line, sizeof line);
      cin.sync();
      cin.clear();

    //determine size of users integer
      inputSize = strlen(line);      

      //check for negative integer value and set bool
      if (inputSize > 0)      
      {
            int negative = '-';
            if (line[0] == negative)
                  isNegative = true;
      }

      //set negative to zero
      if (isNegative)
            line[0] = '0';

      //check that all digits entered where integer values
      for (int loopSize = 0; loopSize < inputSize; loopSize++)
            if (!isdigit(line[(inputSize - 1) - loopSize]))
            {
                  cout << "Not all digits entered where integers.  Array initialized to zero" << endl;
                  return;
            }

      //add digits to array bigNumber
      for (int loopSize = 0; loopSize < inputSize; loopSize++)
            //subtract ASCII value for '0' to get raw value store digits at
            //end of 40 digit array all non initialized parts of array stay a 0
            bigNumber[(arraySize - 1) - loopSize] = line[(inputSize - 1) - loopSize] - '0';
            
}//end input function

ostream &operator<<(ostream &output, const OLHugeInteger &bigNumber2)
{
      // Display negative sign if isNegative is set.
      if (isNegative)
            output << '-';
      
      //if array isZero then print a single zero
      if(isZero())
            output << '0';
      
      bool leadingZero = true;
      
      //avoid printing all leading zero'
      for (int digitIndex = 0; digitIndex < arraySize; digitIndex++)
      {
            int digit = bigNumber[digitIndex];
            //if it is not a zero, print it, and set leadingZero to false;
            if (digit != 0)
            {
                  leadingZero = false;
                  output << digit;
            }//end if
            else
                  //else if digit is zero, print only if not leading
                  if (!leadingZero)
                        output << digit;
                  
      }//end for
      return output;
     
}//end output function