/in/foo.c: In function 'main':
/in/foo.c:11:8: error: expected expression before ']' token
 sort(a[]);
        ^
/in/foo.c: In function 'sort':
/in/foo.c:27:13: error: 'a' undeclared (first use in this function)
 t=x[k];x[k]=a[i];a[i]=t;
             ^
/in/foo.c:27:13: note: each undeclared identifier is reported only once for each function it appears in