Help me convert this to object oriented

[anderfernandes]

All,

I'm having a hard time to convert this to object oriented code. Please don't give me the answer. Just say what I need to do.

#include <iostream>
#include <string>
#include <cmath>
using namespace std;
int parseHex(const string &hexString)
{
int i = 0;
int sum = 0;
int powercount = 0;
int temp = 0;
int count = hexString.length(); // Finds length of string
for(i = count-1; i>=0; i--) // Reads string from right to left.
{
switch(hexString[i])
{
// The switch statement defines each HEX variable.
case 'A': temp = 10;break;
case 'B': temp = 11;break;
case 'C': temp = 12;break;
case 'D': temp = 13;break;
case 'E': temp = 14;break;
case 'F': temp = 15;break;
default:
/* Referenced to ASCII chart - The ascii code inputs of 0 - 9 is 48 - 57.
Therefore, when hexString[i] is anywhere between 48 - 57, taking that number and subtracting 48 will display the right result.*/
if(int(hexString[i]) >= 48 && int(hexString[i]) <= 57)
temp = hexString[i] - 48;
else
cout<<"Error: Lowercase letters will not be accepted."<<endl; // Hex numbers should be capitalized.
}
sum += temp*pow(double(16),double(powercount));
powercount++;
}
return sum;
}
int main()
{
string hexString;
cout<<"Enter in a hex number: "<<endl;
getline(cin,hexString); // input string
cout<<"Decimal Form: "<<parseHex(hexString)<<"\n\n"; // prints converted decimal answer.
system("pause");
}

So far I have:

#include <iostream>
#include <cmath>
#include <string>
using namespace std;

class HexConvert
{
public:
	HexConvert(); // Default Constructor
	HexConvert(string); // Constructor with an object on it
	string getHex(); // Accessor function
	int parseHex(); // Function that will 
	~HexConvert(); // Destructor

private:
	string hexString; // Data field
};

Do I have a good start?