C++ unordered_multimap clear()用法及代码示例

unordered_multimap::clear()是C++ STL中的内置函数，可清除unordered_multimap容器中的内容。调用该函数后，容器的最终大小为0。

用法:

unordered_multimap_name.clear()

参数：该函数不接受任何参数。

返回值：它什么也不返回。

以下示例程序旨在说明上述函数：

示例1:

// C++ program to illustrate the 
// unordered_multimap::clear() 
#include <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
  
    // declaration 
    unordered_multimap<int, int> sample; 
  
    // inserts key an delement 
    sample.insert({ 10, 100 }); 
    sample.insert({ 10, 100 }); 
    sample.insert({ 20, 200 }); 
    sample.insert({ 30, 300 }); 
    sample.insert({ 15, 150 }); 
  
    cout << "Key and Elements of multimap are:"; 
  
    for (auto it = sample.begin(); it != sample.end(); it++) { 
        cout << "\n{" << it->first << ", " << it->second << "}"; 
    } 
  
    sample.clear(); 
  
    cout << "\nSize of container after function call: "
         << sample.size(); 
  
    return 0; 
}

输出：

Key and Elements of multimap are:
{15, 150}
{30, 300}
{20, 200}
{10, 100}
{10, 100}
Size of container after function call: 0

示例2:

// C++ program to illustrate the 
// unordered_multimap::clear() 
#include <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
  
    // declaration 
    unordered_multimap<char, char> sample; 
  
    // inserts element 
    sample.insert({ 'a', 'b' }); 
    sample.insert({ 'a', 'b' }); 
    sample.insert({ 'b', 'c' }); 
    sample.insert({ 'r', 'a' }); 
    sample.insert({ 'c', 'b' }); 
  
    cout << "Key and Elements of multimap are:"; 
  
    for (auto it = sample.begin(); it != sample.end(); it++) { 
        cout << "\n{" << it->first << ", " << it->second << "}"; 
    } 
  
    sample.clear(); 
  
    cout << "\nSize of container after function call: "
         << sample.size(); 
    return 0; 
}

输出：

Key and Elements of multimap are:
{c, b}
{r, a}
{b, c}
{a, b}
{a, b}
Size of container after function call: 0

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 clear() 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。