Map Count Update

Maps associate keys with values, so repeated updates can accumulate a count for one key.

map_count_update.cpp

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

int main() {
    std::string item = ;

    std::map<std::string, int> counts;
    counts[item] += 1;
    counts[item] += 1;

    int count = counts[item];

    std::cout << "item=" << item << std::endl;
    std::cout << "count=" << count << std::endl;
    return 0;
}

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

int main() {
    std::string item = ;

    std::map<std::string, int> counts;
    counts[item] += 1;
    counts[item] += 1;

    int count = counts[item];

    std::cout << "item=" << item << std::endl;
    std::cout << "count=" << count << std::endl;
    return 0;
}

map A `std::map` stores key-value pairs ordered by key.

keyed update Using `counts[key]` creates a value when the key is missing and then lets the program update it.