#include <stdio.h>
	void swap ( double*  , double*   );	/* just a prototype */
	void swap ( double* p, double* q ) {
		double temp;
		temp = *p;
		*p = *q;
		*q = temp;
	}
	
	int main ( int argc, char* argv[] ) {
		double a = 10.1;
		double b = -2.1;
		double* pa;
		double* pb;
		double* ptemp;
	
		printf( "\nThis is the output from %s:", argv[0] );
		printf( "\nThe command line has %d arguments\n\n", argc);
	
		printf( "To begin, a is %5.1f, b is %5.1f\n", a, b );
		swap( &a, &b );
		printf( "After swap(&a, &b), a is %5.1f, b is %5.1f\n", a, b );
	
		pa = &a;
		pb = &b;
	
		printf( "\nNow pa points to an object with value %5.1f,"
		   "\nand pb points to an object with value %5.1f\n", *pa, *pb );
		swap( pa, pb );
		printf( "After swap(pa, pb), a is %5.1f, b is %5.1f\n", a, b );
		printf( "And pa points to an object with value %5.1f,"
		   "\nand pb points to an object with value %5.1f\n", *pa, *pb );
	
		ptemp = pa;
		pa = pb;
		pb = ptemp;
		printf( "\nAfter swaping pa and pb,\npa points to an object with value %5.1f,"
		   "\nand pb pointss to an object with value %5.1f\n", *pa, *pb );
		printf( "But a is %5.1f, b is %5.1f\n", a, b );
		return (0);
	}
	/*
	This is the output from pointer-1:
	The command line has 1 arguments

	To begin, a is  10.1, b is  -2.1
	After swap(&a, &b), a is  -2.1, b is  10.1

	Now pa points to an object with value  -2.1,
	and pb points to an object with value  10.1
	After swap(pa, pb), a is  10.1, b is  -2.1
	And pa points to an object with value  10.1,
	and pb points to an object with value  -2.1

	After swaping pa and pb,
	pa points to an object with value  -2.1,
	and pb points to an object with value  10.1
	But a is  10.1, b is  -2.1
	*/