C++ multiset lower_bound()用法及代码示例

multiset::lower_bound()是C++ STL中的内置函数，该函数返回指向容器中第一个元素的迭代器，该迭代器等效于在参数中传递的k。如果set容器中不存在k，则该函数返回一个迭代器，该迭代器指向刚好大于k的下一个元素。如果传递给参数的键超过了容器中的最大值，则返回的迭代器将打印容器中的元素数。

用法:

multiset_name.lower_bound(key)

参数：该函数接受单个强制性参数键，该键指定要返回其lower_bound的元素。

返回值：该函数返回一个迭代器。

以下示例程序旨在说明上述函数：

程序1:

// CPP program to demonstrate the 
// multiset::lower_bound() function 
#include <bits/stdc++.h> 
using namespace std; 
int main() 
{ 
  
    multiset<int> s; 
  
    // Function to insert elements 
    // in the multiset container 
    s.insert(1); 
    s.insert(2); 
    s.insert(2); 
    s.insert(1); 
    s.insert(4); 
  
    cout << "The multiset elements are:"; 
    for (auto it = s.begin(); it != s.end(); it++) 
        cout << *it << " "; 
  
    // when 2 is present 
    auto it = s.lower_bound(2); 
    cout << "\nThe lower bound of key 2 is "; 
    cout << (*it) << endl; 
  
    // when 3 is not present 
    // points to next greater after 3 
    it = s.lower_bound(3); 
    cout << "The lower bound of key 3 is "; 
    cout << (*it) << endl; 
  
    // when 5 exceeds the max element in multiset 
    it = s.lower_bound(7); 
    cout << "The lower bound of key 7 is "; 
    cout << (*it) << endl; 
  
    return 0; 
}

输出：

The multiset elements are:1 1 2 2 4 
The lower bound of key 2 is 2
The lower bound of key 3 is 4
The lower bound of key 7 is 5

程序2:

// CPP program to demonstrate the 
// multiset::lower_bound() function 
#include <bits/stdc++.h> 
using namespace std; 
int main() 
{ 
  
    multiset<int> s; 
  
    // Function to insert elements 
    // in the multiset container 
    s.insert(1); 
    s.insert(3); 
    s.insert(3); 
    s.insert(5); 
    s.insert(4); 
  
    cout << "The multiset elements are:"; 
    for (auto it = s.begin(); it != s.end(); it++) 
        cout << *it << " "; 
  
    // when 3 is present 
    auto it = s.lower_bound(3); 
    cout << "\nThe lower bound of key 3 is "; 
    cout << (*it) << endl; 
  
    // when 2 is not present 
    // points to next greater after 2 
    it = s.lower_bound(2); 
    cout << "The lower bound of key 2 is "; 
    cout << (*it) << endl; 
  
    // when 10 exceeds the max element in multiset 
    it = s.lower_bound(10); 
    cout << "The lower bound of key 10 is "; 
    cout << (*it) << endl; 
  
    return 0; 
}

输出：

The multiset elements are:1 3 3 4 5 
The lower bound of key 3 is 3
The lower bound of key 2 is 3
The lower bound of key 10 is 5

相关用法

注：本文由纯净天空筛选整理自gopaldave大神的英文原创作品 multiset lower_bound() in C++ STL with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。