map find() function in C++ STL
The map::find() is a built-in function in C++ STL which returns an iterator or a constant iterator that refers to the position where the key is present in the map. If the key is not present in the map container, it returns an iterator or a constant iterator which refers to map.end().
Syntax:
iterator=map_name.find(key)
or
constant iterator=map_name.find(key)
Parameters: The function accepts one mandatory parameter key which specifies the key to be searched in the map container.
Return Value: The function returns an iterator or a constant iterator which refers to the position where the key is present in the map. If the key is not present in the map container, it returns an iterator or a constant iterator which refers to map.end().
Time Complexity for Searching element :
The time complexity for searching elements in std::map is O(log n). Even in the worst case, it will be O(log n) because elements are stored internally as Balanced Binary Search tree (BST) whereas, in std::unordered_map best case time complexity for searching is O(1).
Below is the illustration of the above function:
CPP
// C++ program for illustration// of map::find() function#include <bits/stdc++.h>using namespace std;int main(){ // Initialize container map<int, int> mp; // Insert elements in random order mp.insert({ 2, 30 }); mp.insert({ 1, 40 }); mp.insert({ 3, 20 }); mp.insert({ 4, 50 }); cout << "Elements from position of 3 in the map are : \n"; cout << "KEY\tELEMENT\n"; // find() function finds the position // at which 3 is present for (auto itr = mp.find(3); itr != mp.end(); itr++) { cout << itr->first << '\t' << itr->second << '\n'; } return 0;} |
The elements from position 3 in map are : KEY ELEMENT 3 20 4 50
