C if(a>b)c=a;a=b;b=c;  D if(a>b){c=a;a=b;b=c;}

18.有以下程序

#include <stdio.h>

main()

{ int c=0 ,k;

for (k=1;k<3;k++)

switch (k)

{default:c+=k;

case 2:c++;break;

case 4:c+=2;bre