C++ multimap operator>=

C++ operator>= is a non-member overloaded function of multimap in C++. This function is used to check whether the first multimap is greater than or equal to other or not.

Note: Operator >= sequentially compares the element of multimap and comparison will stop at first mismatch.

Syntax

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 );

Parameter

lhs: First multimap object.

rhs: Second multimap object.

Return value

It returns true if the left side of the multimap container object is greater than or equal to the right side of the multimap container object otherwise false.

Complexity

Complexity will be constant, if the size of lhs and rhs is different.

Otherwise, up to linear in the size (equality comparisons).

Iterator validity

No changes.

Data Races

Containers, lhs and rhs are accessed.

Exception Safety

This function does not throw an exception.

Example 1

Let's see the simple example to check whether the first multimap is greater than or equal to or not:

#include <iostream>
#include <map>

using namespace std;

int main() {
   multimap<char, int> m1;
   multimap<char, int> m2;

   m1.emplace('a', 1);
   m2.emplace('a', 1);

   if (m1 >= m2)
      cout << "Multimap m1 is greater than or equal to m2." << endl;

   m2.emplace('b', 2);

   if (!(m1 >= m2))
      cout << "Multimap m1 is not greater than or equal to m2." << endl;

   return 0;
}

Output:

Multimap m1 is greater than or equal to m2.
Multimap m1 is not greater than or equal to m2.

In the above example, there are two multimaps m1 and m2. m1 and m2 contains one element. When we compare both multimaps then it will display the message "multimap m1 is greater than or equal to m2" and after adding one more element to m2, it will display the message "multimap m1 is not greater than or equal to m2".

Example 2

Let's see a simple example:

#include <map>  
#include <iostream>  
  
using namespace std; 
   
int main( )  
{   
   multimap < int, int > m1, m2, m3, m4;  
   int i;  
   typedef pair < int, int > Int_Pair;  
  
   for ( i = 1 ; i < 3 ; i++ )  
   {  
      m1.insert ( Int_Pair ( i, i ) );  
      m2.insert ( Int_Pair ( i, i * i ) );  
      m3.insert ( Int_Pair ( i, i - 1 ) );  
      m4.insert ( Int_Pair ( i, i ) );  
   }  
  
   if ( m1 >= m2 )  
      cout << "Multimap m1 is greater than or equal to multimap m2." << endl;  
   else  
      cout << "The multimap m1 is less than the multimap m2." << endl;  
  
   if ( m1 >= m3 )  
      cout << "Multimap m1 is greater than or equal to multimap m3." << endl;  
   else  
      cout << "The multimap m1 is less than the multimap m3." << endl;  
  
   if ( m1 >= m4 )  
      cout << "Multimap m1 is greater than or equal to multimap m4." << endl;  
   else  
      cout << "The multimap m1 is less than the multimap m4." << endl;  
      
      return 0;
}

Output:

The multimap m1 is less than the multimap m2.
Multimap m1 is greater than or equal to multimap m3.
Multimap m1 is greater than or equal to multimap m4.

Example 3

Let's see a simple example:

#include <iostream>
#include <map>

using namespace std;

int main()
{
  multimap<char,int> m1, m2;
  m1.insert(make_pair('a',10));
  m1.insert(make_pair('b',20));
  m1.insert(make_pair('a',30));
  m2 = m1;

  cout << (m1 >= m2) << endl;

  m2.insert(make_pair('d',40));

  cout << (m1 >= m2) << endl;

  return 0;
}

Output:

1
0

In the above example if m1 is greater than or equal to m2 then it will return 1 otherwise 0.

Example 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 << "\nWelcome to your Page..." << endl;
   else  
        cout << "\nIncorrect ID or Password..." << endl;
      return 0;
}

Output:

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...

In the above example, there are two multimaps m1 and m2. m1 contains stored ID and password and second multimap m2 stores user's entered ID and password. It checks whether the m1 is greater than or equal to m2 or not. If ID and password of m1 is greater than or equal to m2 then login is successful otherwise login fails.

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