Basic knowledge points of dictionary

1. Using dictionaries （Dictionary）
System.Collections.Generic;// Namespace
2. A dictionary is a mapping from a set of keys to a set ; Any key is unique , Key cannot be empty reference , If the value is of reference type , Can be null ;key and value Can be of any type
3.Dictionary< type 1, type 2> d=new Dictionary< type 1, type 2>（）;
4. Additive elements
d.Add( data 1, data 2);
3. adopt key Look for the element
d.Containskey( key )// Whether there is a value corresponding to the key change
4. adopt keyvaluepair Traverse keys and values
d.key: key
d.value: value
5. Traverse all keys
Dictionary< key , value >.KeyCollection keys=d.keys;
6. Traverse all values
Dictionary< key , value >.valueCollection values=d.Value;
7. Delete the specified key value
d.Remove( key )
Other common properties and methods
compare： Get to determine whether there is an equal in the dictionary
Count: Number of key value pairs
Item: Gets or sets the value of the specified key
keys: The set of keys
values: Collection of values
add: Add key value
Clear： Remove all keys and values
Contains Key： Determines whether the specified key is included
ContainsValue： Determine whether to include the specified value
Gettype: Get key value type