In-depth understanding of C # Indexers (a property that supports parameters) versus attributes

Indexers are a special class member that allows objects to be accessed in an array-like manner, making the program look more intuitive and easier to write.
1, the definition of the indexer
Class members in C # can be any type, including arrays and collections. When a class contains arrays and collection members, the indexer greatly simplifies the access operations of an array or collection member.
The way you define an indexer is similar to defining a property, and its general form is as follows: When the indexer//this represents an array or collection member that operates on this object, it can simply be understood as the name of the indexer, so when the same type is used, the parameters are distinguished.

[modifier] Data type this[index type index]{    get{//get Property Code}      set{//Set property's Code}}

Such as

public int this [int index]{    get{}    set{}}

Specific examples are as follows:

Class z{        //Full set of 100 integers        private long[] arr = new long[100];        Declare indexer public        Long This[int index]        {            get            {//Check index range                if (Index < 0 | | Index <=)                {                    R Eturn 0;                }                else                {                    return arr[index];                }            }            Set            {                if (!) ( Index < 0 | | Index <= 0))                {                    Arr[index] = value;}}   }

2. Use of indexers
You can access an array member of an instance of a class by means of an indexer, which is similar in general form to the following:
Object name [index]
Modifiers include Public,protected,private,internal,new,virtual,sealed,override, Abstract,extern, where the data type of the index must be the same as the index type of the indexer. For example:

Z  z=new  z (); z[0]=100;z[1]=101; Console.WriteLine (z[0]);//indicates that an object z is created first, and then the array elements in the object are referenced by an index.

3. Indexers in the interface
Indexers can also be declared in an interface, and there are two differences between an interface indexer and a class indexer: one is that the interface indexer does not use modifiers, and the interface indexer contains only accessors get or set, without implementing statements. The purpose of the accessor is to indicate whether the indexer is read-write, read-only, or write-only, and if it is read-write, the accessor get or set cannot be omitted, if read-only, the set accessor is omitted, and if it is write-only, the get accessor is omitted.
For example:

Public interface iaddress{    string this[int index]{get;set;    String Address{get;set;}    String Answer ();}

Indicates that the declared interface Iaddress contains 3 members: an indexer, an attribute, and a method in which the indexer is readable and writable.
4. Comparison of indexers and attributes
Indexers and properties are members of a class and are syntactically very similar. Indexers are typically used in custom collection classes to manipulate collection objects by using indexers as easily as arrays, whereas properties can be used with any custom class, which enhances the flexibility of the class's field members.