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Predicate Version of lower_bound

  • 项目

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

template<class ForwardIterator, class T, class Compare> 
   inline ForwardIterator lower_bound(
      ForwardIterator First,
      ForwardIterator Last,
      const T& Value,
      Compare Compare
   )

备注

说明说明

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。

lower_bound 算法返回序列中的第一个位置可以插入此类值序列的顺序维护。lower_bound 返回迭代器确定在位置值在范围 [First可插入。; 如果该位置不存在，Last)，或返回 Last 。此版本假定该范围 [First。使用 比较 功能，Last) 按顺序排序。

示例

// lower_boundPV.cpp
// compile with: /EHsc
// Illustrates how to use the lower_bound function.
//
// Functions:
//    lower_bound : Return the lower bound within a range.

// disable warning C4786: symbol greater than 255 character,
// okay to ignore this warning
#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, location ;

    // Initialize vector Numbers
    Numbers[0] = 4 ;
    Numbers[1] = 10;
    Numbers[2] = 70 ;
    Numbers[3] = 10 ;
    Numbers[4] = 30 ;
    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

    //sort Numbers using the function object less<int>()
    //lower_bound assumes that Numbers is sorted
    //using the "compare" (less<int>() in this case)
    //function
    sort(start, end, less<int>()) ;

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

    // return the first location at which 10 can be inserted
    // in Numbers
    location = lower_bound(start, end, 10, less<int>()) ;

    cout << "First location element 10 can be inserted in Numbers is: "
        << location - start << endl ;
}

Output

Numbers { 4 10 10 30 69 70 96 100  }

First location element 10 can be inserted in Numbers is: 1

要求

**标题:**algorithm

请参见

概念

标准模板库示例