unordered_map empty in C++ STL

unordered_map::empty() function is used to check whether container size is zero or not. If container size is zero then it return TRUE otherwise it return FALSE.
Syntax:

 unordered_map_name.empty()

Parameters: This function does not accept any parameter
Return type: This function returns boolean value TRUE or FALSE.

Examples:

Input: ump = { {1, 2}, {3, 4}, {5, 6}, {7, 8}}
ump.empty();
Output: False

Input: ump = { };
ump.empty();
Output: True

filter_none

edit
close

play_arrow

link
brightness_4
code

// CPP program to illustrate
// Implementation of unordered_map empty() function
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
    // Take any two unordered_map
    unordered_map<int, int> ump1, ump2;
  
    // Inserting values
    ump1[1] = 2;
    ump1[3] = 4;
    ump1[5] = 6;
    ump1[7] = 8;
  
    // Print the size of container
    cout << "ump1 size = " << ump1.size() << endl;
    cout << "ump2 size = " << ump2.size() << endl;
  
    // Running the function for ump1
    if (ump1.empty())
        cout << "True\n";
    else
        cout << "False\n";
  
    // Running the function for ump2
    if (ump2.empty())
        cout << "True\n";
    else
        cout << "False\n";
  
    // Running the function for ump1 after
    // clearing it
    ump1.clear();
    if (ump1.empty())
        cout << "True\n";
    else
        cout << "False\n";
  
    return 0;
}

chevron_right


Output:

ump1 size = 4
ump2 size = 0
False
True
True

Don’t stop now and take your learning to the next level. Learn all the important concepts of Data Structures and Algorithms with the help of the most trusted course: DSA Self Paced. Become industry ready at a student-friendly price.




My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.