C + + small point of knowledge

1. C + + copy constructor parameter is const type

Cause: Because the copy constructor is passed the copied object by reference, the reference is passed the address, so the modification of the reference within the constructor affects the source object and prevents the source object from being modified by setting the parameter type to const

2. Enumeration type

When using enumerations, you will encounter this warning: warning C4482:nonstandard extension used:enum

Reason: nonstandard extension used: Enumeration "enum" is used in qualified names when enumerating within a reference type, you do not need to specify the name of the enumeration. File-scoped enumeration definitions are equivalent to constants and do not require qualified names.

C + + small point of knowledge