CODEWITHSUNDEEP
c++hashmap
djfoxmccloud
djfoxmccloud

Reputation: 599

hash_map value deletion

My question concern memory management.

I got this container :

typedef hash_map<const string, Powerdomain*, strptrhash, strptrequal> PowerdomainHashMap;

now I add one element in it 

PowerdomainHashMap powerdomainMap;
Powerdomain* pd1=new Powerdomain("Powerdomain1");
powerdomainMap.insert(Powerdomain_pair(pd1->getName(),pd1));

After that my program does a first step.

Now that the first step is done, i no longer need the powerdomains and want to delete them.

Is a powerdomainMap.clear() sufficient ? Will it destroy all the value entries in the map (ie call delete on every Powerdomain* in the map?

(I think it is better than calling delete on a iterator on the map but i am not sure)

Upvotes: 1

Views: 1647

Answers (2)

Konrad Rudolph
Konrad Rudolph

Reputation: 545618

Is a powerdomainMap.clear() sufficient ?

No. You have manually acquired memory (using new), you need to manually release it (using delete). Better to use smart pointers instead of raw pointers though (preferably std::shared_ptr).

Upvotes: 3

user2100815
user2100815

Reputation:

No it won't - you need to iterate over the map and call delete on the contents yourself. Or better yet, use a map of smart pointers which will do the delete for you. Another alternative, if you don't need polymorphism, is to use a map of name to values, not pointers, in which case you can lose the dynamic memory management stuff altogether.

Upvotes: 5

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