The C++ function std::unordered_map::insert() extends container by inserting new elements in the unordered_map.
Following is the declaration for std::unordered_map::insert() function form std::unordered_map header.
template <class InputIterator> void insert (InputIterator first,InputIterator last);
first − Input iterator to the initial position in range.
last − Input iterator to the final position in range.
None
Linear i.e. O(n) in average case.
Quadratic i.e. O(N * (size+ 1)) in worst case.
The following example shows the usage of std::unordered_map::insert() function.
#include <iostream> #include <unordered_map> using namespace std; int main(void) { unordered_map<char, int> um1 = { {'a', 1}, {'b', 2}, {'c', 3}, {'d', 4}, {'e', 5}, }; unordered_map<char, int> um2; um2.insert(um1.begin(), um1.end()); cout << "Unordered map contains following elements" << endl; for (auto it = um2.begin(); it != um2.end(); ++it) cout << it->first << " = " << it->second << endl; return 0; }
Let us compile and run the above program, this will produce the following result −
Unordered map contains following elements d = 4 c = 3 b = 2 a = 1 e = 5