set find() Function in C++ STL

// 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;
}