c - Declaring a variable with both register and static storage classes

Question

(ANSI-C 89) Hi, is it possible to declare a variable both static and register ? When ever I try to do this I just get as an error massage: multiple storage classes in declaration specifiers

This is the code:

#include <stdio.h>

void f1(static int i);
int main()
{
    static register int i;

    i = 5;
    f1(i);
}

void f1(static int i)
{
    static int y =6;
    y+=1;
    printf("\n Y=%d \n",y);
}

and th

Answer 1

Both register and static are storage class specifiers, and at most one storage class specifier can be specified.

From the C11 Standard ISO/IEC 9899:2011:

6.7.1 Storage-class specifiers

Syntax

1.      storage-class-specifier:
             typedef
          extern
          static
          _Thread_local
          auto
          register
   

Constraints

2. At most, one storage-class specifier may be given in the declaration specifiers in a declaration, except that _Thread_local may appear with static or extern.¹²⁰⁾

---

¹²⁰⁾_{See ‘‘future language directions’’ (6.11.5).}