unordered_multimap empty() function in C++ STL (original) (raw)

Last Updated : 8 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:

unorderedmultimapname.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 #include 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 #include 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