C + + Learning---const

When a const variable of the same name is defined in two files, two independent variables are defined relative to each other

You want to define a const variable in a file and use it in other files: both declaration and definition, plus the extern keyword

Because the const object cannot be changed once it is initialized, it must be initialized when the const variable is created

A const variable can be assigned to a non-const variable, whereas a const variable is initialized only to a const reference.

C + + Learning---const