谁知道这个用 switch case怎么编程c语言

if (index>=18&&index<25) flag=1;
if(index>=25&&index<30) flag=2;
……
switch(flag)
case 1:printf("正常“）；break；
……

# include <stdio.h>
int main (void)
{
float w, h, z hishu;
int x;
printf("请输入您的体重（千克）\n");
scanf("%f", & w);
printf("请输入您的身高（米）\n");
scanf("%f", & h);
zhishu = w / (h * h);
printf("您的体重指数为:%f\n", zhishu);
if (zhishu >18 && zhishu < 26)
x = 1;
else if (zhishu > 25 && zhishu < 31)
x = 2;
else if (zhishu > 30)
x = 3;
else if (zhishu > 35)
x = 4;
else if (zhishu > 40)
x = 5;
else
x = 6;
switch(x)
{
case 1:
printf("正常体重\n");
break;
case 2:
printf("超重\n");
break;
case 3:
printf("轻度肥胖\n");
break;
case 4:
printf("中度肥胖\n");
break;
case 5:
printf("重度肥胖\n");
break;
case 6:
printf("偏瘦\n");
break;
}
return 0;
}

用if将条件分情况，然后就可以用switch了