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Storage Classes & Sections in C

INTRODUCTION

The storage class determines the part of memory where storage is allocated for an object (particularly variables and functions) and how long the storage allocation continues to exist.
A scope specifies the part of the program which a variable name is visible, that is the accessibility of the variable by its name. In C program, there are four storage classes: automatic, register, external, and static.
The hardware terms we have primary storage such as registers, cache, memory (Random Access Memory) and secondary storage such as Hard Disk and optical Disk.

Variables	Storage Section	Initial Value	Scope	Persistence	miscellaneous Properties
Global initialized	Data	NA	Whole program	Process
Global un-initialized	BSS	0	Whole program	Process
Local initialized	Stack	NA	Block	Block
Local un-initialized	Stack	Garbage	Block	Block
Global static initialized	Data	NA	File	Process
Global static un-initialized	BSS	0	File	Process
Local static initialized	Data	NA	Block	Process
Local static un-initialized	BSS	0	Block	Process
Constants	text	NA	Block	Block
Command line arguments	text	NA	Block	Block
Dynamically allocated (malloc)	heap	Garbage	Whole program	Process
Dynamically allocated (calloc)	heap	0	Whole program	Process
Automatic	stack	Garbage	Block	Block
Volatile	stack	Garbage	Block	Block	Only local variables
Register	stack	Garbage	Block	Block	Only local variables Address can't printed
Extern	NA	No init	Block	Process	Only Global variables Can be added to header files