C

Question

is there any difference in following two instructions: int a; extern int a;

Wim Sturkenboom · Answer

Yes there is. int a will allocate space to store an integer extern int a will not allocate memory to store an integer; it tells the compiler that memory for an int a is already allocated somewhere else (another function). If I recall correctly you will get errors during the linking phase if int a does not exist and the compiler encounters extern int a .