What tasks and limitations are associated with using the unordered_map container in projects?

The unordered_map container in C++ is a hash table that provides fast access to elements by key. Main tasks and limitations when using:

• Tasks:

  • Fast search, insertion, and deletion of elements on average in O(1).
  • Storing key-value pairs with unique keys.

• Limitations:

  • Memory: unordered_map may use more memory due to hash tables and collisions.
  • Element order is not guaranteed — elements are stored in arbitrary order.
  • Performance depends on the quality of the hash function and key distribution.
  • With many collisions, performance can degrade to O(n).
  • Keys must be hashable and comparable for equality.

When using, it is important to choose an appropriate hash function and consider that the order of traversal of elements is not fixed.