unordered_set find() function in C++ STL

The unordered_set::find() function is a built-in function in C++ STL which is used to search for an element in the container. It returns an iterator to the element, if found else, it returns an iterator pointing to unordered_set::end(). 

Syntax :

unordered_set_name.find(key)

Parameter: This function accepts a mandatory parameter key which specifies the element to be searched for. 

Return Value: It returns an iterator to the element if found, else returns an iterator pointing to the end of unordered_set.

Below programs illustrate the unordered_set::find() function: 

Program 1: 

CPP

// C++ program to illustrate the
// unordered_set::find() function

#include <iostream>
#include <string>
#include <unordered_set>

using namespace std;

int main()
{

    unordered_set<string> sampleSet = { "geeks1", "for", "geeks2" };

    // use of find() function
    if (sampleSet.find("geeks1") != sampleSet.end()) {
        cout << "element found." << endl;
    }
    else {
        cout << "element not found" << endl;
    }

    return 0;
}

Output:

element found.

Time Complexity: O(n)

Auxiliary Space: O(n)

Program 2: 

CPP

// CPP program to illustrate the
// unordered_set::find() function

#include <iostream>
#include <string>
#include <unordered_set>

using namespace std;

int main()
{

    unordered_set<string> sampleSet = { "geeks1", "for", "geeks2" };

    // use of find() function
    if (sampleSet.find("geeksforgeeks") != sampleSet.end()) {
        cout << "found" << endl;
    }
    else {
        cout << "Not found" << endl;
    }

    return 0;
}

Output:

Not found

Time Complexity: O(n)

Auxiliary Space: O(n)