應用：計算運費
每公里每噸貨物的基本運費為p(price)，貨物重為w(weight)，距離為s，折扣為d(discount)，則總運費f(freight)的計算公式為 freight=price*weight*s*(1-discount)

#include <stdio.h>
int main()
{
    int c,s;
    float p,w,d,f;
    printf("please enter p,w,s: ");
    scanf("%f%f%d", &p, &w, &s);
    if(s>=3000)
        c=12;
    else
        c=s/250;
    switch (c)
    {
    case 0:
        d=0;break;
    case 1:
        d=2;break;
    case 2:
    case 3:
        d=5;break;
    case 4:
    case 5:
    case 6:
    case 7:
        d=8;break;
    case 8:
    case 9:
    case 10:
    case 11:
        d=10;break;
    case 12:
        d=15;break;
    }
    f=p*w*s*(1-d/100.0);
    printf("freight=%.2f\n", f);
    return 0;
}
 

#include <stdio.h>
#include <math.h>
int main()
{
    double x, y;
    int t;
    scanf("%lf", &x);
    t=(x<2)+(x<6)+(x<10);
    switch(t)
    {
    case 3: //(x<2)、(x<6)、(x<10)全為真時
        y=x;
        break;
    case 2://(x<6)、(x<10)為真時
        y=x*x+1;
        break;
    case 1://僅(x<10)為真時
        y=sqrt(x+1);
        break;
    case 0:  //(x<2)、(x<6)、(x<10)沒有一個為真，即x>=10
        y=1/(x+1);
    }
    printf("%lf\n", y);
    return 0;
}