bind1st 함수

이항 함수의 첫 번째 인수에 지정된 값을 결합하여 이항 함수 개체를 단항 함수 개체로 변환하는 어댑터를 만드는 헬퍼 템플릿 함수

template<class Operation, class Type> 
   binder1st <Operation> bind1st( 
      const Operation& _Func,  
      const Type& _Left 
   );

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.

반환 값

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

설명

Function binders are a kind of function adaptor and, because they return function objects, can be used in certain types of function composition to construct more complicated and powerful expressions.

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 is more convenient.

예제

// functional_bind1st.cpp
// compile with: /EHsc
#include <vector>
#include <functional>
#include <algorithm>
#include <iostream>

using namespace std;

// Creation of a user-defined function object
// that inherits from the unary_function base class
class greaterthan5: unary_function<int, bool>
{
public:
    result_type operator()(argument_type i)
    {
        return (result_type)(i > 5);
    }
};

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 result1a;
    result1a = count_if(v1.begin(), v1.end(), bind1st(less<int>(), 10));
    cout << "The number of elements in v1 greater than 10 is: "
         << result1a << "." << endl;

    // Compare: counting the number of integers > 5 in the vector
    // with a user defined function object
    vector<int>::iterator::difference_type result1b;
    result1b = count_if(v1.begin(), v1.end(), greaterthan5());
    cout << "The number of elements in v1 greater than 5 is: "
         << result1b << "." << endl;

    // Count the number of integers < 10 in the vector
    vector<int>::iterator::difference_type result2;
    result2 = count_if(v1.begin(), v1.end(), bind2nd(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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