Predicate Version of nth_element

在 Visual C++ 演示如何使用 nth_element 标准模板库函数的 (STL)谓词版本。

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

备注

备注

类/参数名在原型不匹配版本在头文件。修改某些提高可读性。

nth_element 算法分区序列 [First。Last) 在 第 n引用的值。 所有元素小于或等于该值在值和大于所有元素之前比值在值后面放置在序列放置。 nth_element 的谓词版本用于比较 比较 功能。

示例

// 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  }

要求

**标题:**algorithm

请参见

概念

标准模板库示例