//	Ex721.cc

//	Sec. 7.2 of lecture
//	Demonstration of function parameters

#include <iostream.h>

//		declare function sgn( <double-var> )
double sgn(double x);		// by value
//double sgn(double& x);	// by reference
//double sgn(const double& x);	// by reference, const. data

//		declare function sgn( <double-var>* )
double sgn(double* x);		// by address
//double sgn(const double* x);	// by address, const. data
//double sgn(const double* const x);	// by address, const. pointer

//------------------------------------------

main()
{
 double a,b, *pa=&a;
 
 cout << endl << " Input Argument      : ";
 cin  >> a;

 b  = sgn(a);		// by value or by reference
 
 cout << " 1:  sgn(" << a << ") = " << b << endl;
 
 b = sgn(&a);		// by address
 
 cout << " 2:  sgn(" << a << ") = " << b << endl;
 
 if (pa==&a)
  {
   cout << endl << "Adress of x remains the same." << endl;
  }

}

//------------------------------------------

//		declare  functions
double sgn(double x)			// value
//double sgn(double& x)			// reference
//double sgn(const double& x)		// const. reference
{
  double y;
  
  if ( x > 0.0 ) 
    {
      y = 1.0 ;
    }
  else
    {
      if ( x == 0.0 )
	{
          y = 0.0 ;
	}
      else
	{
          y = -1.0 ;
	}
    } 
  x++; 		// Demo with different parameter types
  return y;
}

//------------------------------------------

double sgn(double* x)		// by address
//double sgn(const double* x)	// by address, const. data
//double sgn(const double* const x)	// by address, const. pointer
{
  double y;
  
  if ( *x > 0.0 ) 
    {
      y = 1.0 ;
    }
  else
    {
      if ( *x == 0.0 )
	{
          y = 0.0 ;
	}
      else
	{
          y = -1.0 ;
	}
    }  
  (*x)++; 	// Demo with different parameter types
  x++; 		// Demo with different parameter types
  return y;
}