Question

I have a map:

typedef map<string, float> my_map;
my_map maxmap;

I’m trying to find the maximum float value and its corresponding string key. This is how I’m finding the max float value but I get a segmentation fault and also don’t know how to find the corresponding string key.

float max = *(max_element(&(maxmap.begin()->second), &(maxmap.end()->second)));

Thanks a lot!!

Answer 1

maxmap.end()->second <– What your trying to do here is dereference the end iterator which is not valid.

Just use a for loop:

typedef my_map::iterator iter;
iter it = maxmap.begin();
iter end = maxmap.end();

float max_value = it->second;
std::string str = it->first;
for( ; it != end; ++it) {
    if(*it->second > max_value) {
        max_value = it->second;
        str = it->first;
    }
}