Source files (.c files)
C function definitions are placed in source files that have names ending in �.c�.
All functions normally may be accessed (called) by any other function in any file.
A function definition may be preceded by �static� to restrict access so that it may be called only by other functions defined in the same file.
External (�global�) variables may be defined in a .c file outside any function.
- External variables are created when program execution begins;
- they retain their values until execution of the program terminates.
- External variables may also be defined static in order to restrict access to them to the file containing the variable definition.