map and unordered_map

Key–value containers: map keeps keys sorted (tree), unordered_map uses hashing for faster lookups.

Intermediate

std::unordered_map<std::string, int> pins = {{"LED", 13}, {"BUZZER", 8}};
pins["SERVO"] = 9;
if (auto it = pins.find("LED"); it != pins.end())
    std::cout << it->second;    // 13

	`map`	`unordered_map`
Order	sorted by key	none
Lookup	$O(\log n)$	$O(1)$ average

Spotted a mistake or want to add detail? Suggest an improvement — Content Contributors' edits are reviewed by editors before they go live.

Discussion (0)