Indexer, hash table hashtabl, Dictionary dictionary (GO)

First, indexer

Indexers are similar to properties, except that their get accessors take parameters. To declare an indexer on a class or struct, use the This keyword.

Example:

Indexer Sample code///<summary>
The class that stores the day of the week. Declares a get accessor that accepts a string and returns the corresponding integer
</summary>
public class Week
{
Public string[] weeks = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

Indexer it accepts a string of days of the week, it is indexed as index
public int this[string Day]
{
Get accessor and return the corresponding integer
Get
{
int i = 0;

foreach (var item in weeks)
{
if (item = = day)
{
return i;
}
i++;
}

Not found back-1
return-1;
}
}
}

Second, hash table hashtable

HasTable is the implementation of a hash table that can be based on key values, the type of the key is object, and the type of value is object.

Add a Key/value key value pair to the hash table: Hashtableobject.add (Key,value);

Remove a Key/value key value pair in the hash table: Hashtableobject.remove (key);

Remove all elements from the hash table: Hashtableobject.clear ();

Determines whether a hash table contains a specific key key:HashtableObject.Contains (key);

There are two ways to traverse a Hashtable object:

Because Hashtable each element is a key/value pair, the element type is neither the type of the key nor the type of the value, but the DictionaryEntry type.

Hashtable sample Code//Method one
foreach (System.Collections.DictionaryEntry de in myhashtable)
{
Note that the default type stored in Hasttable is object and needs to be converted before it can be output
Console.WriteLine (DE. Key.tostring ());
Console.WriteLine (DE. Value.tostring ());
}


Method Two
System.Collections.IDictionaryEnumerator enumerator = Myhashtable.getenumerator ();

while (enumerator. MoveNext ())
{
Console.WriteLine (Enumerator.       Key); Hashtable key word
Console.WriteLine (Enumerator.      Value); Hashtable value
}

Third, the Dictionary dictionary

Dictionary<tkey,tvalue> is a generic implementation of Hastbale.

Traverse key
foreach (string key in Mydictionary.keys)
{
Iterate over the value of a key
foreach (String val in Mydictionary[key])
{

}
}

Because Dictionary is a collection of keys and values, the element type is not a key type or a value type. Instead, the element type is the KeyValuePair of the key type and the value type.

Dictionary Traversal example foreach (keyvaluepair<string, string> kvp in MyDictionary)
{
String key = Kvp. Key;//key contains the keys in the dictionary.
for (int i = 0; i < KVP. Value.count; i++)
{
Response.Write (KVP. Value[i]);
}
}

Example:

Code

Define a <string,int> dictionary, and let its value be added (or you can use the Add method)
dictionary<string, int> dic = new dictionary<string, int> ();

Add two keys for "score 1", "Score 2", and assign them a value of 0
dic["Score 1"] = 0;
dic["Score 2"] = 0;

Add these two values to 1, respectively.
dic["score 1"]++;
dic["Score 2"]++;

Indexer, hash table hashtabl, Dictionary dictionary (GO)