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_42.cpp | 86 ++++++++++++++++++++++++ 1 file changed, 86 insertions(+) create mode 100644 Bachelor/Prog2/Codebeispiele/7_ch21/fig21_42.cpp (limited to 'Bachelor/Prog2/Codebeispiele/7_ch21/fig21_42.cpp') diff --git a/Bachelor/Prog2/Codebeispiele/7_ch21/fig21_42.cpp b/Bachelor/Prog2/Codebeispiele/7_ch21/fig21_42.cpp new file mode 100644 index 0000000..4dc79f8 --- /dev/null +++ b/Bachelor/Prog2/Codebeispiele/7_ch21/fig21_42.cpp @@ -0,0 +1,86 @@ +// Fig. 21.42: fig21_42.cpp +// Demonstrating function objects. +#include + +using std::cout; +using std::endl; + +#include // vector class-template definition +#include // copy algorithm +#include // accumulate algorithm +#include // binary_function definition + +// binary function adds square of its second argument and +// running total in its first argument, then returns sum +int sumSquares( int total, int value ) +{ + return total + value * value; + +} // end function sumSquares + +// binary function class template defines overloaded operator() +// that adds suare of its second argument and running total in +// its first argument, then returns sum +template< class T > +class SumSquaresClass : public std::binary_function< T, T, T > { + +public: + + // add square of value to total and return result + const T operator()( const T &total, const T &value ) + { + return total + value * value; + + } // end function operator() + +}; // end class SumSquaresClass + +int main() +{ + const int SIZE = 10; + int array[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; + + std::vector< int > integers( array, array + SIZE ); + + std::ostream_iterator< int > output( cout, " " ); + + int result = 0; + + cout << "vector v contains:\n"; + std::copy( integers.begin(), integers.end(), output ); + + // calculate sum of squares of elements of vector integers + // using binary function sumSquares + result = std::accumulate( integers.begin(), integers.end(), + 0, sumSquares ); + + cout << "\n\nSum of squares of elements in integers using " + << "binary\nfunction sumSquares: " << result; + + // calculate sum of squares of elements of vector integers + // using binary-function object + result = std::accumulate( integers.begin(), integers.end(), + 0, SumSquaresClass< int >() ); + + cout << "\n\nSum of squares of elements in integers using " + << "binary\nfunction object of type " + << "SumSquaresClass< int >: " << result << endl; + + 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