Class: A class is a reference type that is allocated on the heap. An instance of a class is assigned just a copy of the reference. Both are pointing to the same segment of the actual object. The memory class has constructors and destructors that can be inherited and inherited.
Structure: The structure is the value type allocated on the stack (although the access speed of the stack is faster than the heap, but the resources of the stack are limited), the assignment of the structure will be assigned to generate a new object. Structures have no constructors, but can be added. A structure without a destructor structure may not inherit from another structure or be inherited, but it can inherit from the interface as a class.
Structure and class association
1, definition and use are very similar
　　 Examples are as follows:
Public struct Student
{
String Name;
Int Age;
}
Public class QuesTIon
{
Int Number;
String Content;
}
use:
Student s=new Student();
QuesTIon q=new QuesTIon();
2. Both are of type container: this means they can contain other data types as members.
3, both have members: including: constructors, methods, properties, fields, constants, enumerated types, events, and event handlers.
4. Both members have their own access scope. For example, you can declare one member as Public and another member as Private.
5, both can achieve the interface.
6. Both can expose a default attribute, but only if the attribute has to acquire at least one argument.
7. Both can declare and trigger events, and both can declare delegates (Delegate).
The difference between structure and class
1, storage type: structure is a value type, stored on the stack. A class is a reference type that is stored on the stack and on the heap. The heap stores the real data, the storage address is stored on the stack, and the value of one reference is modified. The value of the same reference is changed.
2, inheritance: the class can be inherited, it can inherit other classes or interfaces, can also be inherited, and, many of the characteristics of the class is represented by inheritance, to prevent the inheritance of the class, the statement must be displayed sealed. The structure has no inheritance: it cannot inherit another structure or class and cannot be inherited. Because of this, the structure cannot have abstract members. Although the structure is not explicitly declared with a sealed, the structure is implicit. Structures can inherit interfaces, and methods are the same as class inheritance interfaces.
3, initialization: the class can be initialized at the time of declaration, the structure can not be initialized at the time of declaration (cannot initialize the field in the structure), otherwise an error is reported.
4, constructor: class and structure have their own default constructor. In the class, once we have written the parameter constructor, the default constructor does not exist. When we want to call a constructor with no arguments to initialize the object, we must write a constructor with no arguments. But in the structure, there is always a default constructor with no parameters, and this constructor is irreplaceable, can not be rewritten, can not be overwritten, in the structure, we can only write constructors with parameters, can not be written Constructor with no arguments.
5. Destructor: The class has a destructor, but the structure has no destructor.
6, keywords: can be used in the class but the restrictions in the structure of the use of keywords: abstract, sealed, protected; StaTIc keyword can be used in front of the class name to declare static classes, but can not be used in front of the struct, not There is a static structure.
Instructions for useThe structure is stored in the stack, and the stack has one feature, that is, the space is small, but the access speed is faster, the heap space is larger, but the access speed is relatively slow. So when we describe a lightweight object, we can define it as a structure to improve efficiency. Such as points, rectangles, colors, these objects are lightweight objects, because describing them, only a small number of fields are needed. When describing a heavyweight object, we know that the object of the class is stored in the heap space, we define the heavyweight object as a class. They all represent data structures that can contain data members and function members. Unlike classes, structures are value types and do not require heap allocation. A structure type variable directly contains the structure's data, while a class type variable contains a reference to the data (the variable is called an object). The struct type is suitable for representing lightweight objects such as points, rectangles, and colors. Although it is possible to represent a point as a class, the structure is more efficient in some scenarios. In some cases, the cost of the structure is lower. For example, if you declare an array with 1000 point objects, you will allocate additional memory for each object referenced. So the structure is suitable for representing a lightweight object.
Based on the above comparison, we can conclude that some lightweight objects are best used with structs, but it is best to use classes with large amounts of data or complex processing logical objects.
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