11. C # Basic finishing (special collections and hash tables)

Special Collections: Queue, Stack one, stack stack class: Advanced, no index

New Stack ();

1. Add data: Push: Pushes elements into the collection

Ss. Push (3); SS. Push (5); SS. Push (7);

2. Get the data:
(1) Peek returns the object at the top of the stack without removing it (gets the value of the last entered element)

Console.WriteLine (ss. Peek ()); // 7

(2) Pop sets the elements together (read and remove)

Console.WriteLine (ss. Pop ()); // 7 Console.WriteLine (ss. Pop ()); // 5

3. Other operations

ToArray: Returns the array type, converts the elements in the stack to a collection, and then puts them in the array

Object [] Shuzu = (object[]) ss. ToArray (); foreach (object in Shuzu) {Console.WriteLine (a);}

Queuing Queue class: FIFO

1, the definition method:

New Queue ();

2. Increase:

(1) Enqueue put elements at the end of the queue

Q.enqueue (3); Q.enqueue (5); Q.enqueue (7);

(2) Peek: Returns the object at the beginning without removing it

Console.WriteLine ("Peek:"+q.peek ()); // 3

3. Get: Dequeue Remove and return the object at the beginning of the queue

Console.WriteLine ("Dequeue:"+q.dequeue ());

Hash table Hashtable Class

Reading data in pairs with key values, you can set the index yourself

 Hashtable ht = new   Hashtable (); Ht. ADD (  a  , "  zhangsan  ); //  an arbitrary type of key + an arbitrary type of value  ht. ADD ( "  ", "  lisi   ); Ht. ADD (  c  , "  wangwu  ); 

How to print the number of elements in a hash table:

ICollection Htkeys = ht. Keys; Console.WriteLine (Htkeys. Count);

Read key value

// CopyTo---Copied to an array string New string [3];htkeys. CopyTo (SS1,0);

Reading value values

ICollection htvalues = ht. Values; string New string [3];htvalues. CopyTo (SS2,0);

Paired reads: Both key and value need to be redefined

IDictionaryEnumerator ID = ht. GetEnumerator (); // Object Key1=id. Key; // gets a value // object value1 = ID. Value; // ID. MoveNext (); // moves down one element, returns a Boolean value, and can no longer be moved if False  while (ID. MoveNext ()) {object key2=ID. Key; Console.WriteLine (Key2. ToString ()); object value2 = ID. Value; Console.WriteLine (value2. ToString ());}

Ht.   Remove ("B"); --Remove the key based on the key value

11. C # Basic finishing (special collections and hash tables)