switch语句的实际应用和如何解决

switch主要是找到判断条件和数据之间的联系比如第一题将重量除以10后面，数据时0，1,2,3，4就比较好使用
第一题如下：
#include <stdio.h>
int main()
{
double weight,sum,h,l,w;
int data;
scanf("%lf %lf %lf %lf",&l,&w,&h,&weight);
if((l>1)||(w>1)||(h>1)||(weight>40))
{
printf("bu xu you ji\n");
return 0;
}
data = weight/10;
switch(data)
{
case 0:
sum = 5 + 2.5weight;
break;
case 1:
case 2:
sum = 2.510+(weight-10)2+5;
break;
case 3:
case 4:
sum = 2.510+2.020+1.5(weight-30) +5;
break;
}
printf("%.2f\n",sum);
printf("\n");
return 0;
}