A.
int x=0,y=10; switch(x) {case y:x++;break; case y+2:x+=10;break; case y-1:x=-7;break; }
B.
int x=0,y; switch(x) {case x>0:y=1;break; case x==0:y=0;break; case x<0:y=-1;break; }
C.
#define y 20 int x=10,z; switch(x) { case 12:z=3;break; case y+1:x+=10;break; case y-8:y-=3;break; }
D.
int x=0,y; switch(x) {case 3: case -1:y=2;break; case 2:break; }