Map in c++

map : A collection that stores pairs where each pair consists of a first half called a key and second half called a vlues.

- sometimes called a "dictionary","associative array", or "hash"
- usage: add(key,value) pairs; look up a values by supplying a key.

real-world examples:
 - dictionary of words and definations
 - phone book
 - social buddy list.

Map Opration

m.put(key.value) : adds key/value pair to the map.
m.get(key): returns the value paired with the given key.
m.remove(key): removes the given key and its paired value.

Map Vs HashMap

Map - implemented using a linked structure called binary search tree.
 -  pretty fast for all operations; keys are stored in sorted order.
 - both kinds of maps implement exactly the same operations.

HashMap - implemented using a special array called a hash table.
 - very fast but keys are stored in unpredictable order.