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I have STL Multimap, I want to remove entries from the map which has specific value , I do not want to remove entire key, as that key may be mapping to other values which are required.
any help please.
967
erase() is used to remove or erase elements from a multimap container. This function can remove or erase the elements by its key, position or the given range. When we run this function the size of the multimap container is reduced by the number of elements being removed.
multimap::find( ) an inbuilt function in C++ STL, which is defined in <map> header file. find() searches elements in the container which are associated with key K. This function returns an iterator pointing to the single element in a container. It returns an iterator if the element found in the container.
You cannot do that. Multimap in C++ STL is ordered and the order cannot/must not be changed (I think at the bottom line it is using a balanced binary tree for the keys I think, not sure though). What you can do is instantiate a new multimap object passing a comparator that fits your needs (research strict weak order).
} (2) (since C++17) Multimap is an associative container that contains a sorted list of key-value pairs, while permitting multiple entries with the same key. Sorting is done according to the comparison function Compare , applied to the keys.
If I understand correctly these values can appear under any key. If that is the case you'll have to iterate over your multimap and erase specific values.
typedef std::multimap<std::string, int> Multimap; Multimap data; for (Multimap::iterator iter = data.begin(); iter != data.end();) { // you have to do this because iterators are invalidated Multimap::iterator erase_iter = iter++; // removes all even values if (erase_iter->second % 2 == 0) data.erase(erase_iter); } If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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