Learning C + + Primer's personal understanding (11)

Associative containers

　　It's like a dictionary whose elements are key-value pairs. The keyword plays an index role.

　　

　Ordered:

Map: associative arrays; Pao-value pairs

Set: The keyword is both a value.

Multimap: keyword-repeatable map

Multiset: The keyword can repeat the set

　　

　Disordered:

Unordered_ First Four

Using map

　　Map<sring,size_t> Word_count;

Using Set

　　Set<string> Exclude

Pair type

　　A pair type holds two data members.

When creating a pair, we must provide two class names.

Pair type has two members

First

Second

　

Associative container iterators

　　When we dereference an iterator for an associative container, we get a reference to the value of the value_type of the container type.

For map, is a pair type, first save the const keyword, second save the value.

The set iterator is a const

adding elements

　　The insert member of the associated container adds an element or an element range to the container.

　　

　　

Learning C + + Primer's personal understanding (11)