The differences between structs and classes in C + +

In C + +, a struct is a special form of a class.

The only difference between structs and classes is that structs and classes have different default access control properties .

　　class , the access control property for a member that does not specify an access control property is a private type (private)

　　struct , the access control property for a member that does not specify any access control properties is public type

in C + +, the inability to use structs does not affect the ability of the program to express . C + + is introduced to the structure to maintain compatibility with C programs.

However, structs are still used in C + + because structs can be used to compose different types of data to make it easier to save data. (If you save with a class, it is cumbersome to read and overwrite individual properties for each data member-specific function because the members of the class are private by default.) ）

Structs in C are not allowed to define function members, and there is no concept of access control properties.

C + + introduces the object-oriented features such as member functions, access control permissions, inheritance, polymorphism, and so on, in C language structure.

C + + introduces the class keyword outside of the struct, but in order to maintain compatibility with the C program, C + + retains the struct keyword and specifies that the struct's default access control permissions are public types.

In addition,in C, the size of the empty struct is 0, while the C + + hollow struct (which belongs to the empty Class) is 1.

The reason for the size of the empty class in C + + is 1:

An empty class can also be instantiated, and each object instantiated by the class needs to have a different memory address, so that each object has a different address in memory, so an implied byte is added to the class.

The differences between structs and classes in C + +