cpp02.cpp

C++参考书

// Coded by plusir -- Dec.29.2002.
// Standard C++ Bible -- (P211-7-2)

#include <iostream>
#include <cmath>
#include <cerrno>
using namespace std ;

int main()
{
	double f ;

	do {
		errno = 0 ;
		cout << "Enter positive float( 0 to quit ): " ;
		cin >> f ;

		if ( f != 0 ) {
			double sq = sqrt( f ) ;
			if ( errno == 0 )
				cout << "Square root of " << f << " is " << sq << endl ;
			else
				cout << "Invalid entry" << endl ;
		}
	} while ( f!= 0 ) ;

	return 0 ;
}