C++ unordered_multimap find()用法及代码示例

unordered_multimap::find()是C++ STL中的内置函数，该函数返回一个迭代器，该迭代器指向具有键k的元素之一。如果容器不包含键为k的任何元素，则它将返回一个迭代器，该迭代器指向经过容器中最后一个元素的位置。

用法:

unordered_multimap_name.find(k)

参数：该函数接受指定 key 的强制参数k。

返回值：它返回一个迭代器，该迭代器指向具有键k的元素所在的位置。

以下示例程序旨在说明上述函数：

示例1:

// C++ program to illustrate the 
// unordered_multimap::find() function 
#include <iostream> 
#include <unordered_map> 
using namespace std; 
  
int main() 
{ 
  
    // declaration 
    unordered_multimap<int, int> sample; 
  
    // inserts key and element 
    sample.insert({ 1, 2 }); 
    sample.insert({ 1, 2 }); 
    sample.insert({ 2, 3 }); 
    sample.insert({ 3, 4 }); 
    sample.insert({ 2, 6 }); 
  
    // find the element with key 1 and print 
    auto it = sample.find(1); 
    if (it != sample.end()) 
        cout << 1 << ":" << it->second << endl; 
    else
        cout << "element with key 1 not found\n"; 
  
    // find the element with 
    // key 2 and print 
    it = sample.find(2); 
    if (it != sample.end()) 
        cout << 2 << ":" << it->second << endl; 
    else
        cout << "element with key 2 not found\n"; 
  
    // find the element with 
    // key 100 and print 
    it = sample.find(100); 
    if (it != sample.end()) 
        cout << 100 << ":" << it->second << endl; 
    else
        cout << "element with key 100 not found\n"; 
    return 0; 
}

输出：

1:2
2:6
element with key 100 not found

示例2:

// C++ program to illustrate the 
// unordered_multimap::find() 
#include <iostream> 
#include <unordered_map> 
using namespace std; 
  
int main() 
{ 
  
    // declaration 
    unordered_multimap<char, char> sample; 
  
    // inserts element 
    sample.insert({ 'a', 'b' }); 
    sample.insert({ 'a', 'b' }); 
    sample.insert({ 'a', 'd' }); 
    sample.insert({ 'b', 'e' }); 
    sample.insert({ 'b', 'd' }); 
  
    // find the element with 
    // key r and print 
    auto it = sample.find('r'); 
    if (it != sample.end()) 
        cout << "r"
             << ":" << it->second << endl; 
    else
        cout << "element with key r not found\n"; 
  
    // find the element with 
    // key a and print 
    it = sample.find('a'); 
    if (it != sample.end()) 
        cout << 'a' << ":" << it->second << endl; 
    else
        cout << "element with key a not found\n"; 
  
    // find the element with 
    // key 'b' and print 
    it = sample.find('b'); 
    if (it != sample.end()) 
        cout << "b"
             << ":" << it->second << endl; 
    else
        cout << "element with key b not found\n"; 
  
    return 0; 
}

输出：

element with key r not found
a:d
b:d

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 unordered_multimap find() function in C++ STL。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。