The storage class in C are the one which defines the scope or life time of the variable and functions

Four Different storage classes of C are :

• Auto 
• Register
• Static 
• Extern

Auto Storage Class 

Auto storage class are the one which are default for local variables

For example :

{
   int mount;
   auto int month;
}

Register storage Class 

The variables which are stored in registers instead of RAM they have Rigster Storage Class.

Register storage classe defined only for them. The size of the variables then depands on the register size.

{
   register int  miles;
}

If the variables are required frequent memory access then they are atored in the regiaters.Like counters.

Static Storage classes

The static storage classes are to keep the local variable scope in existence till the program execution ends, instead of creating and destroying each time variable is used.

#include <stdio.h>
 

void func(void);
 
static int count = 5;
 
main() {

   while(count--) {
      func();
   }
	
   return 0;
}

void func( void ) {

   static int i = 5;
   i++;

   printf("i is %d and count is %d\n", i, count);
}

The extern storage classes 

It is used to give the reference to a global variable i.e., visible to all other files of the program files.

When you use extern you cannot initialized the variable.