Code walkthrough

The following line declares a map with a string name as the key and a long mobile number as the value stored in the map:

map< string, long > contacts;

The following code snippet adds four contacts organized by name as the key:

 contacts[ "Jegan" ] = 1234567890;
 contacts[ "Meena" ] = 5784433221;
 contacts[ "Nitesh" ] = 4567891234;
 contacts[ "Sriram" ] = 8901122334;

The following line will try to locate the contact with the name, Sriram, in the contacts map; if Sriram is found, then the find() function will return the iterator pointing to the location of the key-value pair; otherwise it returns the contacts.end() position:

 auto pos = contacts.find( "Sriram" );

The following code verifies whether the iterator, pos, has reached contacts.end() and prints the contact number. Since the map is an associative container, it stores a key=>value pair; hence, pos->first indicates the key and pos->second indicates the value:

 if ( pos != contacts.end() )
      cout << "\nMobile number of " << pos->first << " is " << pos->second << endl;
 else
      cout << "\nContact not found." << endl;