A.
switch(pow(a,2)+pow(b,2)) /* pow( )为求幂的函数 */ { case 1: case 3: y=a+b; break; case 0: case 5: y=a-b; }
B.
switch(a*a+b*b); { case 3: case 1: y=a+b; break; case 0: y=b-a; break; }
C.
switch a { default: x=a+b; case 10: y=a-b; break; case 11: x=a*b; break; }
D.
switch(a+b) { case10: x=a+b; break; case11: y=a-b; break; }