C++ unordered_multimap size()用法及代码示例

unordered_multimap::size()是C++ STL中的内置函数，该函数返回unordered_multimap的大小。它表示该容器中元素的数量。

用法:

unordered_multimap_name.size()

参数：该函数不接受任何参数。

返回值：它返回一个整数值，该值表示容器的大小。

以下示例程序旨在说明上述函数：

示例1:

// C++ program to illustrate the 
// unordered_multimap::size() 
#include <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
  
    // declaration 
    unordered_multimap<int, int> sample1, sample2; 
  
    // inserts key and element 
    // in sample1 
    sample1.insert({ 10, 100 }); 
    sample1.insert({ 50, 500 }); 
  
    // inserts key and element 
    // in sample1 
    sample2.insert({ 20, 200 }); 
    sample2.insert({ 30, 300 }); 
    sample2.insert({ 30, 150 }); 
  
    cout << "The size of Sample1 is: " << sample1.size(); 
  
    cout << "\nKey and Elements of Sample1 are:"; 
    for (auto it = sample1.begin(); it != sample1.end(); it++) { 
        cout << "{" << it->first << ", " << it->second << "} "; 
    } 
  
    cout << "\n\nThe size of Sample2 is: " << sample2.size(); 
  
    cout << "\nKey and Elements of Sample2 are:"; 
    for (auto it = sample2.begin(); it != sample2.end(); it++) { 
        cout << "{" << it->first << ", " << it->second << "} "; 
    } 
  
    return 0; 
}

输出：

The size of Sample1 is: 2
Key and Elements of Sample1 are:{50, 500} {10, 100} 

The size of Sample2 is: 3
Key and Elements of Sample2 are:{20, 200} {30, 150} {30, 300}

示例2:

// C++ program to illustrate the 
// unordered_multimap::size() 
#include <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
  
    // declaration 
    unordered_multimap<char, char> sample1, sample2; 
  
    // inserts key and element 
    // in sample1 
    sample1.insert({ 'a', 'A' }); 
    sample1.insert({ 'g', 'G' }); 
  
    // inserts key and element 
    // in sample1 
    sample2.insert({ 'b', 'B' }); 
    sample2.insert({ 'c', 'C' }); 
    sample2.insert({ 'd', 'D' }); 
  
    cout << "The size of Sample1 is: " << sample1.size(); 
  
    cout << "\nKey and Elements of Sample1 are:"; 
    for (auto it = sample1.begin(); it != sample1.end(); it++) { 
        cout << "{" << it->first << ", " << it->second << "} "; 
    } 
  
    cout << "\n\nThe size of Sample2 is: " << sample2.size(); 
  
    cout << "\nKey and Elements of Sample2 are:"; 
    for (auto it = sample2.begin(); it != sample2.end(); it++) { 
        cout << "{" << it->first << ", " << it->second << "} "; 
    } 
  
    return 0; 
}

输出：

The size of Sample1 is: 2
Key and Elements of Sample1 are:{g, G} {a, A} 

The size of Sample2 is: 3
Key and Elements of Sample2 are:{d, D} {b, B} {c, C}

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 size() 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。