c2_main.cpp

来自「essential c++ 书上代码和习题答案」· C++ 代码 · 共 46 行

/**************************************************
 * Essential C++ -- Stanley Lippman
 * Addison-Wesley 
 * ISBN 0-201-48518-4
 * homepage: www.objectwrite.com
 * email: [e-mail]
 *************************************************/

#include <iostream>
using namespace std;

bool fibon_elem( int pos, int &elem )
{

	if ( pos <= 0 || pos > 1024 )
	{
		 cerr << "invalid position: " << pos 
			  << " -- cannot handle request!\n";

         elem = 0;
         return false;
	}

    elem = 1; 
    int n_2 = 1, n_1 = 1;
    for ( int ix = 3; ix <= pos; ++ix ) 
    {
		 elem = n_2 + n_1;
		 n_2 = n_1; n_1 = elem;
    }  
	
    return true;
}

bool print_sequence( int pos ) 
{
	if ( pos <= 0 || pos > 1024 ){
		 cerr << "invalid position: " << pos 
			  << " -- cannot handle request!\n";
         return false; 
	}

   cout << "The Fibonacci Sequence for "
        << pos << " positions: \n\t";

   // prints