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multimap empty() function in C++ STL
In this article, we will be discussing the working, syntax, and examples of multimap::empty() function in C++ STL.
What is Multimap in C++ STL?
Multimaps are the associative containers, which are similar to map containers. It also facilitates to store the elements formed by a combination of key-value and mapped value in a specific order. In a multimap container there can be multiple elements associated with the same key. The data is internally always sorted with the help of its associated keys.
What is multimap::empty()?
multimap::empty() function is an inbuilt function in C++ STL, which is defined in <map>header file. empty() is used to check whether the associated multimap container is empty or not.
This function checks if the size of the container is 0 then returns true, else if there are some values then it returns false.
Syntax
map_name.empty();
Parameters
The function accepts no parameter.
Return value
This function returns true if the map is empty and false if it is not.
Input
multimap<char, int > newmap; newmap.insert(make_pair(‘A’, 10)); newmap.insert(make_pair(‘B’, 20)); newmap.insert(make_pair(‘C’, 30)); mymap.empty();
Output
false
Input
std::multimap<int> mymap; mymap.empty();
Output
true
Example
#include<iostream>
#include<map>
using namespace std;
int main(){
multimap<int,int > mul_1;
//inserting elements to multimap1
mul_1.insert({1,10});
mul_1.insert({2,20});
mul_1.insert({3,30});
mul_1.insert({4,40});
mul_1.insert({5,50});
if(mul_1.empty()){
cout<<"\nMultimap is empty";
}
else{
cout<<"\nMultimap is not empty";
cout<<"\nElements in multimap1 are: "<<"\n";
for(auto i= mul_1.begin(); i!= mul_1.end(); i++){
cout<<(*i).first<<" "<< (*i).second << "\n";
}
}
}Output
If we run the above code it will generate the following output −
Multimap is not empty Elements in multimap1 are: 1 10 2 20 3 30 4 40 5 50
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