returns the number of items within a collection
Many collections just store this value explicitely, making this a very cheap operation.
But there are collections which must traverse all its contents to compute the total number of stored items, making this a very expensive operation!
| std::is_empty | checks whether a collection contains any items |
| std_types::association_list | returns the number of items in the association list |
| std_types::hash_set | returns the number of items in the hash set |
| std_types::hash_table | returns the number of items in the hash table |
| std_types::key_order_set | returns the number of items in the key-order set |
| std_types::key_order_table | returns the number of items in the key-order table |
| std_types::list | returns the number of items within the list |
| std_types::octet_string | returns the number of items within the list |
| std_types::quad_octet_string | returns the number of items within the list |
| std_types::value_range | returns the number of values within the range |