binder2nd 類別

提供建構函式的類別範本，藉由將二進位函式的第二個自變數系結至指定的值，將二元函式物件轉換成一元函式物件。 C++11 中已被取代，C++17 中已移除。

語法

template <class Operation>
class binder2nd
    : public unaryFunction <typename Operation::first_argument_type,
    typename Operation::result_type>
{
    typedef typename Operation::argument_type argument_type;
    typedef typename Operation::result_type result_type;
    binder2nd(
        const Operation& func,
        const typename Operation::second_argument_type& right);

    result_type operator()(const argument_type& left) const;
    result_type operator()(argument_type& left) const;
};

參數

func
要轉換為一元函式物件的二元函式物件。

right
二元函式物件的第二個引數所要繫結的值。

left
調整後的二元物件用來與第二個引數的固定值進行比較的引數值。

傳回值

一元函式物件，從將二進位函式物件的第二個自變數系結至值 右邊所產生。

備註

類別範本會在 中op儲存二進位函式物件 func 的複本，並在 中value儲存許可權的複本。 它會將其成員函 operator() 式定義為傳 op(left, value)回 。

如果 func 是 型Operation別的物件，而 c 是常數，則 bind2nd(func, c) 相當於類別建binder2nd構函binder2nd<Operation>(func, c)式 ，而且更方便。

範例

// functional_binder2nd.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(),
        binder2nd<greater<int> >(greater<int>(), 10));
    cout << "The number of elements in v1 greater than 10 is: "
         << result1 << "." << endl;

    // Compare using binder1st fixing 1st argument:
    // count the number of integers < 10 in the vector
    vector<int>::iterator::difference_type result2;
    result2 = count_if(v1.begin(), v1.end(),
        binder1st<greater<int> >(greater<int>(), 10));
    cout << "The number of elements in v1 less than 10 is: "
         << result2 << "." << endl;
}

The vector v1 = ( 0 5 10 15 20 25 )
The number of elements in v1 greater than 10 is: 3.
The number of elements in v1 less than 10 is: 2.