set::count() Function in C++ STL

set find() Function in C++ STL

Last Updated : 13 Feb, 2025

The std::set::find() is a built-in function in C++ STL that is used to find an element in the set container. It is a member function of std::set container so we can use it directly with any set object.

Syntax

 set_name.find(key)

Parameters

key: The element which we have to find.

Return Value

If the element is found, it returns an iterator to its position in the set.
If the element is not found, then it returns the iterator to the end.

Finding elements in a set is straightforward with the find() function.

Example of set::find()

C++

// C++ program to demonstrate the use of
// set::find() function
#include <bits/stdc++.h>
using namespace std;

int main() {

    // Create a set
    set<int> st;
    st.insert(11);
    st.insert(14);
    st.insert(2);
    st.insert(15);
    st.insert(3);

    // key1 find (exist in the set)
    int key1 = 3;

    // key2 find (does not exist in the set)
    int key2 = 1;

    // Check if key1 is found
    if (st.find(key1) != st.end())
        cout << "Key '" << key1 << "' found" << endl;

    // Element not present
    else
        cout << "Key '" << key1 << "' not found!" << endl;

    // Check if key2 is found
    if (st.find(key2) != st.end())
        cout << "Key '" << key2 << "' found" << endl;

    // key2 not found
    else
        cout << "Key '" << key2 << "' not found!" << endl;

    return 0;
}

Output

Key '3' found
Key '1' not found!

Complexity Analysis of set::find()

Time Complexity: O(log n), where n is the number of elements.
Space Complexity: O(1)

set::count() Function in C++ STL

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