C++ flat_set::find() Function

The std::flat_set::find() function in C++, is used to search for a specific element within a flat_set. If the element is found, it returns an iterator pointing to it, orelse it returns an iterstor to the end of the set.

Unlike, std::set, flat_set stores the elements in the sorted vector-like structure, providing efficient memory usage and cache locality. The time complexity of this function is O(log n).

Syntax

Following is the syntax for std::flat_set::find() function.

iterator find( const Key& key );
or
const_iterator find( const Key& key ) const;

Parameters

• key − It indicates the key value of the element to search for.

Return Value

This function returns an iterator to the requested element.

Example 1

Let's look at the following example, where we are going to consider the basic usage of the find() function.

#include <iostream>
#include <boost/container/flat_set.hpp>
int main() {
   boost::container::flat_set < int > a = {12,23,34,45};
   auto x = a.find(23);
   if (x != a.end()) {
      std::cout << "Element Found: " << * x << std::endl;
   } else {
      std::cout << "Element Not Found" << std::endl;
   }
   return 0;
}

Output

Output of the above code is as follows −

Element Found: 23

Example 2

Consider the following example, where we are going to search for the element that does not exist and observing the output.

#include <iostream>
#include <boost/container/flat_set.hpp>
int main() {
   boost::container::flat_set < int > a = {1,3,5};
   auto x = a.find(2);
   if (x != a.end()) {
      std::cout << "Element Found: " << * x << std::endl;
   } else {
      std::cout << "Element Not Found" << std::endl;
   }
   return 0;
}

Output

Following is the output of the above code −

Element Not Found