From 33613a85afc4b1481367fbe92a17ee59c240250b Mon Sep 17 00:00:00 2001 From: Sven Eisenhauer Date: Fri, 10 Nov 2023 15:11:48 +0100 Subject: add new repo --- Bachelor/Prog2/Codebeispiele/7_ch21/fig21_40.CPP | 82 ++++++++++++++++++++++++ 1 file changed, 82 insertions(+) create mode 100644 Bachelor/Prog2/Codebeispiele/7_ch21/fig21_40.CPP (limited to 'Bachelor/Prog2/Codebeispiele/7_ch21/fig21_40.CPP') diff --git a/Bachelor/Prog2/Codebeispiele/7_ch21/fig21_40.CPP b/Bachelor/Prog2/Codebeispiele/7_ch21/fig21_40.CPP new file mode 100644 index 0000000..e1d8a91 --- /dev/null +++ b/Bachelor/Prog2/Codebeispiele/7_ch21/fig21_40.CPP @@ -0,0 +1,82 @@ +// Fig. 21.40: fig21_40.cpp +// Using a bitset to demonstrate the Sieve of Eratosthenes. +#include + +using std::cin; +using std::cout; +using std::endl; + +#include + +using std::setw; + +#include // bitset class definition +#include // sqrt prototype + +int main() +{ + const int size = 1024; + int value; + std::bitset< size > sieve; + + sieve.flip(); + + // perform Sieve of Eratosthenes + int finalBit = sqrt( sieve.size() ) + 1; + + for ( int i = 2; i < finalBit; ++i ) + + if ( sieve.test( i ) ) + + for ( int j = 2 * i; j < size; j += i ) + sieve.reset( j ); + + cout << "The prime numbers in the range 2 to 1023 are:\n"; + + // display prime numbers in range 2-1023 + for ( int k = 2, counter = 0; k < size; ++k ) + + if ( sieve.test( k ) ) { + cout << setw( 5 ) << k; + + if ( ++counter % 12 == 0 ) + cout << '\n'; + + } // end outer if + + cout << endl; + + // get value from user to determine whether value is prime + cout << "\nEnter a value from 1 to 1023 (-1 to end): "; + cin >> value; + + while ( value != -1 ) { + + if ( sieve[ value ] ) + cout << value << " is a prime number\n"; + else + cout << value << " is not a prime number\n"; + + cout << "\nEnter a value from 2 to 1023 (-1 to end): "; + cin >> value; + + } // end while + + return 0; + +} // end main + +/************************************************************************** + * (C) Copyright 1992-2003 by Deitel & Associates, Inc. and Prentice * + * Hall. All Rights Reserved. * + * * + * DISCLAIMER: The authors and publisher of this book have used their * + * best efforts in preparing the book. These efforts include the * + * development, research, and testing of the theories and programs * + * to determine their effectiveness. The authors and publisher make * + * no warranty of any kind, expressed or implied, with regard to these * + * programs or to the documentation contained in these books. The authors * + * and publisher shall not be liable in any event for incidental or * + * consequential damages in connection with, or arising out of, the * + * furnishing, performance, or use of these programs. * + *************************************************************************/ \ No newline at end of file -- cgit v1.2.3