prime.cpp

C++上机课的习题答案

// prime.cpp
//输出1-10000的质数，用函数判断一个数是否是质数。 
#include <iostream>

using std::cout;
using std::endl;

#include <iomanip>

using std::setw;

/* write prototype for function prime */

int main()
{
   int count = 0;

   cout << "The prime numbers from 1 to 10000 are:\n";

   for ( int loop = 2; loop <= 10000; ++loop )

      if ( /* make call to function prime */ ) {
         ++count;
         cout << setw( 6 ) << loop;
      
         if ( count % 10 == 0 )
            cout << '\n';

      } // end if

   cout << '\n' << "There were " << count 
        << " prime numbers\n";

   system("PAUSE");
   return 0;

} // end main

// function prime definition
bool prime( int n )
{
   for ( int i = 2; /* write loop condition */; i++ )

      if ( /* write code to test if n is divisible by i */ )
         return false;

   return true;   // number is prime

} // end function prime