Master static, volatile, sizeof, and I2C for Embedded C

static keyword

The static specifier can be applied to local variables, global variables, functions, and class members. When used with a local variable, it makes the variable persist for the lifetime of the program and stores it in the static data area; initialization occurs before main starts and destruction happens when the program exits.

Applied to a global variable, static does not change its storage location (global variables are already in the static area) but limits its linkage to the translation unit, preventing other files from accessing it.

When placed before a function definition, the function gains internal linkage, meaning it can be called only from the file where it is defined.

For class members, static makes the data member shared by all instances of the class (including derived classes). Static data members must be defined outside the class, e.g., int Base::var = 10;. Static member functions do not have a this pointer and can only access other static members.