Storage class specifier

Storage class specifiers tells the compiler where to store a variable, how to store the variable, what is the initial value of the variable and life time of the variable. 

Types of storage class specifier in c :

 There are four storage class specifier in C Language. They are,
1. Automatic
2. Register
3. Static
4. Extern

S.No.	Storage Specifier	Storage place	Initial / default value	Scope	Life
1	auto	CPU Memory	Garbage value	local	Within the function only.
2	extern	CPU memory	Zero	Global	Till the end of the main program. Variable definition might be anywhere in the C program
3	static	CPU memory	Zero	local	Retains the value of the variable between different function calls.
4	register	Register memory	Garbage value	local	Within the function

• For faster access of a variable, it is better to go for register specifiers rather than auto specifiers.
• Because, register variables are stored in register memory whereas auto variables are stored in main CPU memory.
• Only few variables can be stored in register memory. So, we can use variables as register that are used very often in a C program.