What differs static and global variable storagewise

Santoshkb · 01-15-2012, 01:02 AM

What differs in storage of global vs static in memory layout,
please correct me.

Global variable stored in data segment.
* uninitialized seg - if uninitialized
* initialized segment - if initialized at defination itself.

Static variable in data segment
always initialized segment; (bec for unitialized it initializes to zero)

But how it cases permission restriction within source file(for static) or across process(global).

Any field in symbol table?

Thanks much in adv
-Santosh

ta0kira · 01-15-2012, 02:53 AM

Are you talking about C? If so, the static qualifier prevents linking to the symbol from any other compilation unit. If you don't use the static storage class, the symbol implicitly has external linkage. When using gcc, static is equivalent to __attribute__ ((visibility ("hidden"))).
Kevin Barry

johnsfine · 01-15-2012, 07:40 AM

If this is C, global and static are the same for memory layout and initialization. Either is initialized to zero if not explicitly initialized.

Traditional C implementations have a special segment for global and static variables that were not explicitly initialized. That entire segment is zeroed at load time, because that is more efficient than zeroing individual variables.