C++ Programming - Functions

#include<iostream.h> 
long FactFinder(long = 5); 
int main()
{
    for(int i = 0; i<= 0; i++)
        cout<< FactFinder() << endl; 
    return 0;
}
long FactFinder(long x)
{
    if(x < 2)
        return 1; 
    long fact = 1; 
    for(long i = 1; i <= x-1; i++)
        fact = fact * i; 
    return fact; 
}

#include<iostream.h>
double BixFunction(double, double, double = 0, double = 0, double = 0);
int main()
{
    double d = 2.3;
    cout<< BixFunction(d, 7) << " ";
    cout<< BixFunction(d, 7, 6) << endl;
    return 0; 
}
double BixFunction(double x, double p, double q, double r, double s)
{
    return p +(q +(r + s * x)* x) * x;
}

#include<iostream.h> 
int main()
{
    float Amount;
    float Calculate(float P = 5.0, int N = 2, float R = 2.0);
    Amount = Calculate(); 
    cout<< Amount << endl; 
    return 0;
}

float Calculate(float P, int N, float R)
{
    int Year = 1;
    float Sum = 1 ;
    Sum = Sum * (1 + P * ++N * R);
    Year =  (int)(Year + Sum);
    return Year; 
}

#include<iostream.h> 
class Bix
{
    int x, y; 
    public:
    void show(void);
    void main(void);
};
void Bix::show(void)
{ 
    Bix b;
    b.x = 2;
    b.y = 4;
    cout<< x << " " << y;
}
void Bix::main(void)
{
    Bix b;
    b.x = 6; 
    b.y = 8;
    b.show();
}
int main(int argc, char *argv[])
{
    Bix run;
    run.main();
    return 0; 
}

#include<iostream.h> 
class IndiabixSample
{
    private:
    int AdditionOne(int x, int y = 1) 
    {
        return x * y;
    }
     
    public:
    int AdditionTwo(int x, int y = 1)
    {
        return x / y;
    } 
}; 
int main()
{
    IndiabixSample objBix;
    cout<<objBix.AdditionOne(4, 8)<<" "; 
    cout<<objBix.AdditionTwo(8, 8); 
    return 0;
}