如何将std :: map值复制到非容器数组中？

Question

I have a map that is populated with an id, and an array of floats. I'd like to copy the floats (pair.second) into *temp_arr.

// Temp object
struct Temp
{
    float t1, t2, t3; 
    float n1, n2, n3;
};

// A map that is populated.
std::map<int, Temp> temps;

// temps gets populated ...

int i = 0;
Temps *temp_arr = new Temp[9];

// currently, I do something like ...
for (auto& tmp : temps)
    temp_arr[i++] = tmp.second;

// here's what I tried ...
std::for_each(temps.begin(), temps.end(), [&](std::pair<int, Temp> &tmp) {
        temp_arr[i++] = tmp.second;
});   

I was trying to do this using std::copy and I think a lambda would be needed to get a map of tmp.seconds into the temp_arr, but so far, not yet.

Answer 1

std::copy isn't appropriate here. Instead, you can use std::transform :

std::transform(temps.begin(), temps.end(), temp_arr,
               [](const std::pair<const int, Temp>& entry) {
                   return entry.second;
               });