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Predicate Version of nth_element

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說明如何使用述詞的版本的 nth_element Visual C++ 標準樣板程式庫 (STL) 函式。

template<class RandomAccessIterator, class Compare>
   inline void nth_element(
      RandomAccessIterator First,
      RandomAccessIterator Nth,
      RandomAccessIterator Last,
      Compare compare
   )

備註

注意事項注意事項

在原型中的類別/參數名稱不相符的標頭檔中的版本。某些已修改以提高可讀性。

nth_element演算法的分割區順序 [First...Last) 所參考的值在開次 n。 小於或等於值會放在值之前的所有項目，且大於值的所有項目會放置在序列中的值之後。 述詞的版本的nth_element會使用比較進行比較的函式。

範例

// nth_elementPV.cpp
// compile with: /GX
// Illustrates how to use the predicate version
// of the nth_element function.
//
// Functions:
//    nth_element : Partition the elements in a sequence by its nth
//                  element.

// disable warning C4786: symbol greater than 255 character,
// okay to ignore
#pragma warning(disable: 4786)

#include <iostream>
#include <algorithm>
#include <functional>
#include <vector>

using namespace std;


int main()
{
    const int VECTOR_SIZE = 8 ;

    // Define a template class vector of int
    typedef vector<int > IntVector ;

    //Define an iterator for template class vector of strings
    typedef IntVector::iterator IntVectorIt ;

    IntVector Numbers(VECTOR_SIZE) ;

    IntVectorIt start, end, it ;

    // Initialize vector Numbers
    Numbers[0] = 4 ;
    Numbers[1] = 10;
    Numbers[2] = 70 ;
    Numbers[3] = 30 ;
    Numbers[4] = 10;
    Numbers[5] = 69 ;
    Numbers[6] = 96 ;
    Numbers[7] = 100;

    start = Numbers.begin() ;   // location of first
                                // element of Numbers

    end = Numbers.end() ;       // one past the location
                                // last element of Numbers

    cout << "Before calling nth_element:\n" << endl ;

    // print content of Numbers
    cout << "Numbers { " ;
    for(it = start; it != end; it++)
        cout << *it << " " ;
    cout << " }\n" << endl ;

    // partition the elements by the 4th element
    nth_element(start, start+4, end, less<int>()) ;

    cout << "After calling nth_element:\n" << endl ;

    cout << "Numbers { " ;
    for(it = start; it != end; it++)
        cout << *it << " " ;
    cout << " }\n" << endl ;
}

Output

Before calling nth_element:

Numbers { 4 10 70 30 10 69 96 100  }

After calling nth_element:

Numbers { 4 10 10 30 69 70 96 100  }

需求

標頭: <algorithm>

請參閱

概念

標準樣板程式庫範例