//	Ex710.cc

//	Sec. 7.1 of lecture
//	Demonstration of function declaration and definition

#include <iostream.h>

double sgn(double x);	// declare function sgn // prototype

double sgn(double x);	// 2nd identical declaration possible

// double sgn(double& x);	// not allowed in this context !! 
// int sgn(double x);		// not allowed in this context  !!

double sgn(double* x);	// declaration of another, not used, sgn function
			//   different type of argument


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

 b  = sgn(a);		// function call
 
 cout << "  sgn(" << a << ") = " << b << endl;
}

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

double sgn(double x)	// definition of function sgn
{
 double y;		// local variable
 
 y = (x > 0 ? 1. : 0.) + (x < 0 ? -1. : 0.);
 
 return y;		// return value of function sgn
}