C + + Extern/static/const

1. Static

Static variables, which allocate memory in the static area, are not stored in the stack area.

Static declarations and definitions are carried out at the same time.

The static modified global variables are visible only in the compilation unit itself, and other compilation units are invisible. If you define a static variable in a header file, all the cells that include the header file have a copy of their own, i.e. the physical address of the respective variable is different. So the general definition of the static global variable is defined in the source file instead of the header file, avoiding contamination to other units .

C + + Extern/static/const