#include <iostream>
#include <map>
#include <string>

int main() {
    std::map<std::string, int> stock{{"apple", 5}, {"pear", 2}};
    stock["kiwi"] = 7;                          // insert or overwrite
    stock["apple"] += 1;
    stock.insert({"pear", 100});                // no effect: key exists
    stock.emplace("fig", 3);

    for (const auto& [fruit, qty] : stock) std::cout << fruit << '=' << qty << ' ';   // sorted by key
    std::cout << '\n';

    if (auto it = stock.find("kiwi"); it != stock.end()) std::cout << "kiwi: " << it->second << '\n';
    std::cout << stock.count("mango") << ' ' << stock.contains("fig") << '\n';
    stock.erase("pear");
    std::cout << stock.size() << ' ' << stock.at("fig") << '\n';
}

apple=6 fig=3 kiwi=7 pear=2
kiwi: 7
0 1
3 3

#include <iostream>
#include <map>
#include <string>
int main() {
    std::map<std::string, int> ages{{"ada", 36}};
    if (ages["bob"] == 0) std::cout << "bob not found?\n";   // [] INSERTS "bob" with 0!
    std::cout << ages.size() << '\n';
    // const std::map<...>& cref = ages; cref["x"];          // error: no const operator[]
    try { std::cout << ages.at("cy"); } catch (const std::out_of_range&) { std::cout << "at() throws\n"; }
}

bob not found?
2
at() throws

#include <iostream>
#include <map>
#include <sstream>
#include <string>

int main() {
    std::istringstream text("the cat and the hat and the bat");
    std::map<std::string, int> freq;
    std::string w;
    while (text >> w) ++freq[w];
    for (const auto& [word, n] : freq) std::cout << word << ':' << n << ' ';
    std::cout << '\n';

    std::map<int, std::string> events{{900, "standup"}, {1200, "lunch"}, {1500, "review"}, {1800, "gym"}};
    for (auto it = events.lower_bound(1000); it != events.upper_bound(1600); ++it)   // keys in [1000, 1600]
        std::cout << it->first << ' ' << it->second << '\n';
}

and:2 bat:1 cat:1 hat:1 the:3
1200 lunch
1500 review

#include <iostream>
#include <map>
#include <string>
int main() {
    std::multimap<std::string, std::string> phone{{"ada", "111"}, {"bob", "222"}, {"ada", "333"}};
    auto [first, last] = phone.equal_range("ada");     // all entries with key "ada"
    for (auto it = first; it != last; ++it) std::cout << it->second << ' ';
    std::cout << phone.count("ada") << '\n';
}

111 333 2