Create your own unary function : predicate « STL Introduction « C++ Tutorial

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C++ Tutorial » STL Introduction » predicate 
14.9.1.Create your own unary function
#include <iostream>
#include <list>
#include <functional>
#include <algorithm>
using namespace std;

class reciprocal: unary_function<double, double{
public:
  result_type operator()(argument_type i)
  
    return (result_type1.0/i;
  }
};

int main()
{
  list<double> vals;

  for(int i=1; i<10; i++vals.push_back((double)i);

  cout << "Original contents of vals:\n";
  list<double>::iterator p = vals.begin();
  while(p != vals.end()) {
    cout << *p << " ";
    p++;
  }
  cout << endl;
 
  // use reciprocal function object
  p = transform(vals.begin(), vals.end(),
                vals.begin(),
                reciprocal())// call function object

  cout << "Transformed contents of vals:\n";
  p = vals.begin();
  while(p != vals.end()) {
    cout << *p << " ";
    p++;
  }

  return 0;
}
Original contents of vals:
1 2 3 4 5 6 7 8 9
Transformed contents of vals:
1 0.5 0.333333 0.25 0.2 0.166667 0.142857 0.125 0.111111
14.9.predicate
14.9.1.Create your own unary function
14.9.2.use generic function as predicate
14.9.3.Function object to process the mean value
14.9.4.Illustrating the use of an adaptor for pointers to functions
14.9.5.Use predicate, which returns whether an integer is a prime number, with a list
14.9.6.Convenience function for the compose_f_gx adapter
14.9.7.Convenience function for the compose_f_gx_hx adapter
14.9.8.Convenience function for the compose_f_gx_hy adapter
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