C - External variables2
External variables ...
- If the program is in several source files, and a global variable is defined in file1.c and used in file2.c and file3.c, then extern declarations are needed in file2.c and file3.c to connect the occurrences of the variable.
- The ANSI C standard calls this as external linkage.
- In C, all functions are global and provide external linkage by default.