The C++ function std::unordered_map::operator= copy elements from initializer list to unordered_map.
Following is the declaration for std::unordered_map::operator= function form std::unordered_map header.
unordered_map& operator=(intitializer_list<value_type> il);
il − Initialize list.
Returns this pointer
Linear i.e. O(n) in average case.
Quadratic i.e. O(n2) in worst case.
The following example shows the usage of std::unordered_map::operator= function.
#include <iostream> #include <unordered_map> using namespace std; int main(void) { unordered_map<char, int> um; um = { {'a', 1}, {'b', 2}, {'c', 3}, {'d', 4}, {'e', 5} }; cout << "Unordered map contains following elements: " << endl; for (auto it = um.cbegin(); it != um.cend(); ++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: e = 5 d = 4 c = 3 b = 2 a = 1