unordered_multimap empty() function in C++ STL
The unordered_multimap::empty() is a built-in function in C++ STL which returns a boolean value. It returns true if the unordered_multimap container is empty. Otherwise, it returns false.
Syntax:
unordered_multimap_name.empty()
Parameters: The function does not accept any parameter.
Return Value: It returns a boolean value which denotes whether a unordered_multimap is empty or not.
Below programs illustrates the above function:
Program 1:
// C++ program to illustrate the // unordered_multimap::empty() function #include <iostream> #include <unordered_map> using namespace std; int main() { // declaration unordered_multimap< int , int > sample; // inserts key and element sample.insert({ 1, 2 }); sample.insert({ 1, 2 }); sample.insert({ 2, 3 }); sample.insert({ 3, 4 }); sample.insert({ 5, 6 }); // if not empty then print the elements if (sample.empty() == false ) { cout << "Key and Elements: " ; for ( auto it = sample.begin(); it != sample.end(); it++) { cout << "{" << it->first << ":" << it->second << "} " ; } } // container is erased completely sample.clear(); if (sample.empty() == true ) cout << "\nContainer is empty" ; return 0; } |
Output:
Key and Elements: {5:6} {3:4} {2:3} {1:2} {1:2} Container is empty
Program 2:
// C++ program to illustrate the // unordered_multimap::empty() #include <iostream> #include <unordered_map> using namespace std; int main() { // declaration unordered_multimap< char , char > sample; // inserts element sample.insert({ 'a' , 'b' }); sample.insert({ 'a' , 'b' }); sample.insert({ 'g' , 'd' }); sample.insert({ 'r' , 'e' }); sample.insert({ 'g' , 'd' }); // if not empty then print the elements if (sample.empty() == false ) { cout << "Key and elements: " ; for ( auto it = sample.begin(); it != sample.end(); it++) { cout << "{" << it->first << ":" << it->second << "} " ; } } // container is erased completely sample.clear(); if (sample.empty() == true ) cout << "\nContainer is empty" ; return 0; } |
Output:
Key and elements: {r:e} {g:d} {g:d} {a:b} {a:b} Container is empty
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