C Storage class specifier
C datatypes also supports storage class. Storeage classes desires variable's location and visibility. Default storage class is auto, Auto type of variables are accessible only within function.
Different types of C storage class specifier
Storage class Usage
auto It is default storage class. variables are accessiable within functions.
static Static variables are generally retains its values even after the control is transferred to the calling function.
Extern Extern variables are global variables. It is accessible by all functions.
Register Register variables are local variables which is stored in the register memory.
auto int a; and int c; are same, because default storage class is auto. a,b and c variables are accessiable only within function.
auto int a = 10;
auto int b = 20;
c = a + b;