LANGUAGE » CPP

Dictionary

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Reference:devdocs.io

Basic ​

Includes for unordered_map and map:

cpp
#include <unordered_map>
#include <map>

Instantiate:

cpp
std::unordered_map<std::string, int> my_unordered_map;
std::map<std::string, int> my_ordered_map = {
    {"first", 4},
    {"second", 11},
};

Access values:

cpp
auto value = my_dict["first"];

Adding new key/value pairs:

cpp
my_dict["first"] = 3;
my_dict["second"] = 10;

Delete a key/value pair:

cpp
my_dict.erase("first");

Get number of key/value pairs:

cpp
my_dict.size();

Loop all key/value pairs:

cpp
for (const auto &pair : my_dict) {
    fmt::println("{}: {}", pair.first, pair.second);
}

// Can also be written as:
for (auto it = my_dict.begin(); it != my_dict.end(); ++it) {
    fmt::println("{}: {}", it->first, it->second);
}

Methods ​

MethodDescription
findTakes a key and tries to locate the element with which the key matches.
endIterator that points one past the last element.

Check if a dictionary contains a key:

cpp
if (my_dict.find("first") != my_dict.end()) {
    fmt::println("first found!");
}