Link error with really simple functions C++ on .h file

Question

I\'ve made two functions to \'cast\' a 32/64 bit pointer into a double. The code worked when used alone (Just the .h and a .cpp including it) but when using the .h somewhere

Answer 1

The canonical way to would be:

floatcast.h

#pragma once
#ifndef __FLOATCAST_H
#define __FLOATCAST_H

//A quick and dirty way of casting pointers into doubles and back
//Should work with BOTH 64bit and 32bit pointers
union ptr_u {
    double d;
    void* p;
};

double ptr2double(void* pv);
void* double2ptr(double dv);

#endif

floatcast.cpp

#include "floatcast.h"

double ptr2double(void* pv){
    ptr_u ptr;
    ptr.p = pv;
    return (ptr.d);
};

void* double2ptr(double dv){
    ptr_u ptr;
    ptr.d = dv;
    return(ptr.p);
};