binder1st 클래스

이항 함수의 첫 번째 인수에 지정된 값을 결합하여 이항 함수 개체를 단항 함수 개체로 변환하는 생성자를 제공하는 템플릿 클래스

template<class Operation>
class binder1st
   : public unary_function <
      typename Operation::second_argument_type,
      typename Operation::result_type> 
  {
   public:
   typedef typename Operation::argument_type argument_type;
   typedef typename Operation::result_type result_type;
   binder1st(
      const Operation & _Func,
      const typename Operation::first_argument_type& _Left
   );
   result_type operator()(
      const argument_type& _Right
   ) const;
   result_type operator()(
      const argument_type& _Right
   ) const;
   protected:
   Operation op;
   typename Operation::first_argument_type value;
   };

매개 변수

• _Func
  The binary function object to be converted to a unary function object.

• _Left
  The value to which the first argument of the binary function object is to be bound.

• _Right
  The value of the argument that the adapted binary object compares to the fixed value of the second argument.

반환 값

The unary function object that results from binding the first argument of the binary function object to the value _Left.

설명

The template class stores a copy of a binary function object _Func in op, and a copy of _Left in value. It defines its member function operator() as returning op(value, _Right).

If _Func is an object of type Operation and c is a constant , then bind1st ( _Func, c ) is equivalent to the binder1st class constructor binder1st<Operation> ( _Func, c ) and more convenient.

예제

// functional_binder1st.cpp
// compile with: /EHsc
#include <vector>
#include <functional>
#include <algorithm>
#include <iostream>

using namespace std;

int main()
{
    vector<int> v1;
    vector<int>::iterator Iter;

    int i;
    for (i = 0; i <= 5; i++)
    {
        v1.push_back(5 * i);
    }

    cout << "The vector v1 = ( ";
    for (Iter = v1.begin(); Iter != v1.end(); Iter++)
        cout << *Iter << " ";
    cout << ")" << endl;

    // Count the number of integers > 10 in the vector
    vector<int>::iterator::difference_type result1;
    result1 = count_if(v1.begin(), v1.end(),
        binder1st<less<int> >(less<int>(), 10));
    cout << "The number of elements in v1 greater than 10 is: "
         << result1 << "." << endl;

    // Compare use of binder2nd fixing 2nd argument:
    // count the number of integers < 10 in the vector
    vector<int>::iterator::difference_type result2;
    result2 = count_if(v1.begin(), v1.end(),
        binder2nd<less<int> >(less<int>(), 10));
    cout << "The number of elements in v1 less than 10 is: "
         << result2 << "." << endl;
}

요구 사항

헤더: <기능>

네임스페이스: std

참고 항목

참조

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