map::clear() in C++ STL
Map is dictionary like data structure. It is an associative array of (key, value) pair, where only single value is associated with each unique key.
map::clear()
clear() function is used to remove all the elements from the map container and thus leaving it’s size 0.
Syntax:
map1.clear() where map1 is the name of the map. Parameters: No parameters are passed.
Return Value: None
Examples:
Input : map1 = {
{1, "India"},
{2, "Nepal"},
{3, "Sri Lanka"},
{4, "Myanmar"}
}
map1.clear();
Output: map1 = {}
Input : map2 = {}
map2.clear();
Output: map2 = {}
// CPP program to illustrate // Implementation of clear() function #include <bits/stdc++.h> using namespace std; int main() { // Take any two maps map<int, string> map1, map2; // Inserting values map1[1] = "India"; map1[2] = "Nepal"; map1[3] = "Sri Lanka"; map1[4] = "Myanmar"; // Print the size of map cout<< "Map size before running function: \n"; cout << "map1 size = " << map1.size() << endl; cout << "map2 size = " << map2.size() << endl;; // Deleting the map elements map1.clear(); map2.clear(); // Print the size of map cout<< "Map size after running function: \n"; cout << "map1 size = " << map1.size() << endl; cout << "map2 size = " << map2.size(); return 0; } |
Output:
Map size before running function: map1 size = 4 map2 size = 0 Map size after running function: map1 size = 0 map2 size = 0
Time complexity: Linear i.e. O(n)
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