map with const keys but non const values?

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半阙折子戏 2021-01-12 18:00

I have a situation, where I would like to have a map that does not allow to add/remove keys after initialization, but the values are allowed to change (thus I cannot simply

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花落未央 (楼主)

2021-01-12 18:44
I usually regard this as a pitfall in C++ more than a feature, but, if it fits your application, you can just use pointer values.
```
#include 
#include 

int main(int argc, char ** argv)
{
    using namespace std;
    const map> myMap = { {1, make_shared(100)} };
    // *(myMap[1]) = 2;  // Does not compile
    *(myMap.at(1)) = 2;
    for (auto & element : myMap)
    {
        *(element.second) = 0;
    }
    return 0;
}
```
Which is really just a simpler version of this other answer (obviously you may choose between shared_ptr / unique_ptr as needed).
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