Last Updated : 08 Aug, 2018
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: CPP
// 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: CPP
// 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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