无涯教程-C++ Multimap - operator!=函数 C++ operator！= 是Multimap的非成

C++ operator！= 是Multimap的非成员重载函数。此函数用于检查两个multimap是否相等。

Note: multimap对象之间的比较基于元素的成对比较。如果两个映射具有相同数量的元素并且其对应元素具有相同的值，则它们是相等的。否则，它们是不相等的。

operator!= - 语法

template <class Key, class T, class Compare, class Alloc>  
  bool operator!= ( const multimap<Key,T,Compare,Alloc>& lhs,  
                    const multimap<Key,T,Compare,Alloc>& rhs );

operator!= - 参数

lhs :第一个multimap对象。

rhs :第二个multimap对象。

operator!= - 返回值

如果multimap对象的左侧等于multimap对象的右侧，则返回true，否则返回false。

operator!= - 例子1

让我们看一个简单的示例，检查两个multimap是否相等:

#include <iostream>  
#include <map>  
  
using namespace std;  
  
int main() {  
   multimap<char, int> m1;  
   multimap<char, int> m2;  
  
   m1.emplace(a, 1);  
  
   if (m1 != m2)  
      cout << "Both multimaps are not equal." << endl;  
  
   m1 = m2;  
  
   if (!(m1 != m2))  
      cout << "Both multimaps are equal." << endl;  
  
   return 0;  
}

输出:

Both multimaps are not equal.
Both multimaps are equal.

在上面的示例中，有两个multimapm1和m2。 m1包含一个元素，m2为空。当我们比较两个multimap时，它将显示消息"Both multimap are not equal"，将m1分配给m2后，两个multimap具有相等的元素，则它将显示消息"Both multimap are equal"。

operator!= - 例子2

让我们看一个简单的例子:

#include <map>    
#include <iostream>    
    
int main ()    
{    
   using namespace std;    
   multimap <int, int> m1, m2, m3;    
   int i;    
   typedef pair <int, int> Int_Pair;    
    
   for (i = 0; i <3; i ++)    
   {    
      m1.insert (Int_Pair (i, i));    
      m2.insert (Int_Pair (i, i * i));    
      m3.insert (Int_Pair (i, i));    
   }    
    
   if (m1!= m2)    
      cout << "The multimaps m1 and m2 are not equal." << endl;    
   else    
      cout << "The multimaps m1 and m2 are equal." << endl;    
    
   if (m1!= m3)    
      cout << "The multimaps m1 and m3 are not equal." << endl;    
   else    
      cout << "The multimaps m1 and m3 are equal." << endl;    
        
      return 0;  
}

输出:

The multimaps m1 and m2 are not equal.
The multimaps m1 and m3 are equal.

operator!= - 例子3

让我们看一个简单的例子:

#include <iostream>  
#include <map>  
using namespace std;  
  
int main()  
{  
  multimap<int,char> m1, m2;  
  
  m1.insert(make_pair(1,a));  
  m1.insert(make_pair(2,b));  
  m1.insert(make_pair(3,c));  
  
  m2 = m1;  
  
  cout << (m1 != m2) << endl;  
  
  m2.insert(make_pair(4,d));  
  
  cout << (m1 != m2) << endl;  
  
  return 0;  
}

输出:

0
1

在上面的示例中，如果m1和m2相等，则它将返回1，否则返回0。

operator!= - 例子4

#include <map>    
#include <iostream>    
  
using namespace std;   
    
int main ()    
{    
   multimap<int,string> m2;  
   typedef multimap<int,string> login;   
     
  m2.insert({2040, "xyz@123"}) ; //stored id and password  
     
   string password;  
   int id;  
   login m1;  
     
       cout<<"---------Login----------"<<endl<<endl;  
       cout<<"Enter the ID and password: \n";  
       cin>> id;     //Get key  
       cin>> password;   //Get value  
       m1.insert({id, password});  //Put them in multimap  
  
     cout<<"ID and password you have entered: \n";  
     for (auto it = m1.begin(); it != m1.end(); it++) {  
        cout << (*it).first << "    " << (*it).second << endl;  
      }  
  
      cout<<"ID and Password stored in the system :\n";  
     for (auto it = m2.begin(); it != m2.end(); it++) {  
        cout << (*it).first << "    " << (*it).second << endl;  
     }  
  
    
   if (m1 != m2)    
      cout << "\nIncorrect ID or Password..." << endl;    
   else    
      cout << "\nWelcome to your Page..." << endl;   
        
      return 0;  
}

输出:

1). ---------Login----------

Enter the ID and password: 1020 xyz ID and password you have entered: 1020 xyz ID and Password stored in the system: 2040 xyz@123

Incorrect ID or Password...

2). ---------Login----------

Enter the ID and password: 2040 xyz@123 ID and password you have entered: 2040 xyz@123 ID and Password stored in the system: 2040 xyz@123

Welcome to your Page...

在上面的示例中，有两个multimapm1和m2。 m1包含存储的ID和密码，第二个multimapm2存储用户输入的ID和密码。它检查两个multimap是否具有相同的元素。如果ID和密码匹配，则登录成功，否则，登录失败。

无涯教程-C++ Multimap - operator!=函数