Can't access Global Function from within Class
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06-07-2021 - |
Question
I've created a global function, CallPrice(args). I have a class, EuropeanOption, and I have a class function called CallPrice, which should call the global function using variables from the EuropeanOption class, and return the CallPrice. I'm getting an error, "the global scope has no "CallPrice".
I think this is a common problem. I searched other threads, which said adding :: should solve the problem, but it's not working here for me. Could you identify the cause of the error? Do I need to make this a friend function or some other workaround?
Thanks!
Header:
#ifndef EuropeanOption_HPP
#define EuropeanOption_HPP
#include <iostream>
#include <string>
#include <vector>
#include <cmath>
#include <boost/math/distributions/normal.hpp>
using namespace boost::math;
using namespace std;
namespace CLARK
{
struct EquityParms
{
double T; // years until expiry
double K; // strike price
double sig; // vol
double r; // risk free rate
double b; // cost of carry
};
// Global Call function
const double CallPrice(double T, double K, double sig, double r, double b, double EquityPrice);
class EuropeanOption
{
private:
double T; // years until expiry
double K; // strike price
double sig; // vol
double r; // risk free rate
double b; // cost of carry
double S; // current equity price
double ExactCallPrice;
public:
EuropeanOption(); // default constructor (empty)
EuropeanOption(const EquityParms& data, double EquityPrice); // constructor that sets parms
void copy(const EuropeanOption& source);
~EuropeanOption();
void init(const EquityParms& data, double EquityPrice); // initialize EquityParms
const double CallPrice(); // trying to call global function in this function
};
}
#endif
Source:
#include "EuropeanOption_H.hpp"
namespace CLARK
{
const double CallPrice(double T, double K, double sig, double r, double b, double EquityPrice)
{// Global Function
double temp = sig * sqrt(T);
double d1 = (log(EquityPrice / K) + (r + (sig*sig) * 0.5) * T) / temp;
double d2 = d1 - temp;
normal_distribution<> myNormal(0,1);
return (EquityPrice * cdf(myNormal,d1)) - (K * exp((b - r) * T) * cdf(myNormal, d2));
}
EuropeanOption::EuropeanOption()
{// default constructor
cout << "Default constructor call" << endl;
}
EuropeanOption::EuropeanOption(const EquityParms& data, double EquityPrice)
{// constructor that sets parms
init(data, EquityPrice);
}
void EuropeanOption::copy(const EuropeanOption& source)
{
T = source.T;
K = source.K;
sig = source.sig;
r = source.r;
S = source.S;
b = source.b;
}
EuropeanOption::~EuropeanOption()
{
}
void EuropeanOption::init(const EquityParms& data, double EquityPrice)
{
T = data.T;
K = data.K;
sig = data.sig;
r = data.r;
S = EquityPrice;
b = data.b;
}
const double EuropeanOption::CallPrice()
{ // trying to call global function in this function
return ::CallPrice(T, K, sig, r, b, S); // the global scope has no "CallPrice" ???
}
}
La solution
CallPrice
is in namespace CLARK
. So try
CLARK::CallPrice(/* ... */);
Autres conseils
You have declared the global CallPrice
in the namespace CLARK
. The syntax ::CallPrice
tries to use a function CallPrice
defined in the global namespace, or an anonymous namespace. Instead, use CLARK::CallPrice
.
You are in the namespace CLARK:
return CLARK::CallPrice(T, K, sig, r, b, S);