#include <string>
#include <map>

int main()
{
     std::map<std::string, int> mapCityTemperature;
     // A key of type std::string
     // A value with type int

     mapCityTemperature["Berlin"] = 22;
     mapCityTemperature["Paris"] = 27;
     mapCityTemperature["Singapore"] = 32;
     mapCityTemperature["Moscow"] = 19;
}

int temperature = mapCityTemperature["Singapore"];
// temperature = 32

temperature = mapCityTemperature["singapore"]; // No value found
// Singapore and singapore are distinguished by uppercase and uppercase letters
// temperature = 0

auto pItem = mapCityTemperature.find("Hello");
// not found
if (pItem == mapCityTemperature.end())
{
}

pItem = mapCityTemperature.find("Singapore");
// Found by key
if (pItem != mapCityTemperature.end())
{
     std::string key = pItem->first;
     // key = "Singapore"

     int value = pItem->second;
     // value = 32
}

for (auto pItem = mapCityTemperature.begin(); pItem != mapCityTemperature.end(); pItem++)
{
     std::string key = pItem->first;
     int value = pItem->second;

     // key = "Berlin"
     // value = 22
     // ...
}