Find mapped value of map

c++ dictionary find stdmap
wrongusername picture wrongusername · Nov 24, 2010 · Viewed 86.1k times · Source

Is there a way in C++ to search for the mapped value (instead of the key) of a map, and then return the key? Usually, I do someMap.find(someKey)->second to get the value, but here I want to do the opposite and obtain the key (the values and keys are all unique).

Answer

Bill Lynch picture Bill Lynch · Nov 24, 2010

Because of how a map is designed, you'll need to do the equivalent of a search on unordered data.

for (auto it = someMap.begin(); it != someMap.end(); ++it)
    if (it->second == someValue)
        return it->first;

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