c++ - What happens when we try to erase non existent key from hash_set -

what happens when try erase non existent key hash_set class sgi's stl? call hash_set::erase first try find key , delete it?

here code used implementation of hash_set, it's erase method of hashtable :

template <class _val, class _key, class _hf, class _ex, class _eq, class _all> typename hashtable<_val,_key,_hf,_ex,_eq,_all>::size_type  hashtable<_val,_key,_hf,_ex,_eq,_all>::erase(const key_type& __key) {   const size_type __n = _m_bkt_num_key(__key);   _node* __first = _m_buckets[__n];   size_type __erased = 0;    if (__first) {     _node* __cur = __first;     _node* __next = __cur->_m_next;     while (__next) {       if (_m_equals(_m_get_key(__next->_m_val), __key)) {         __cur->_m_next = __next->_m_next;         _m_delete_node(__next);         __next = __cur->_m_next;         ++__erased;         --_m_num_elements;       }       else {         __cur = __next;         __next = __cur->_m_next;       }     }     if (_m_equals(_m_get_key(__first->_m_val), __key)) {       _m_buckets[__n] = __first->_m_next;       _m_delete_node(__first);       ++__erased;       --_m_num_elements;     }   }   return __erased; } 

as can see, tries find key before deleting node, , does nothing if key doesn't exist.

also, sgi documentation :

erase key : destroys elements key same k, , removes them a. return value number of elements erased, i.e. old value of a.count(k).