如何对各种输入使用不同的计算

Question

我正在写一个程序，让用户输入各种类型的信息来计算度假旅行的费用。

我得到了三种不同交通方式的成本，以及四个源城市和四个目的地城市的成本。

这三种旅行方式是航空、火车和公共汽车，而来源城市是巴尔的摩、查塔努加、纳什维尔和帕萨迪纳。目的地城市是丹佛、麦迪逊、克拉克斯维尔和诺克斯维尔。

我需要能够根据用户输入的内容(旅行形式和每个城市)来计算每个来源和每个目的地城市之间的旅行成本。

现在，我的第一个猜测是为每个条件编写一个非常长的if/else if语句。我试过了，但它似乎不起作用，因为它太长了，或者我在哪里搞砸了。

if(transportation_type == 'A', 'a' && src_city == 'B', 'b' && dest_city == 'D', 'd')
        transportation_price = 5000;

    else if(transportation_type == 'A', 'a' && src_city == 'B', 'b' && dest_city == 'M', 'm')
        transportation_price = 4000;

    else if(transportation_type == 'A', 'a' && src_city == 'B', 'b' && dest_city == 'K', 'k')
        transportation_price = 5000;

    else if(transportation_type == 'A', 'a' && src_city == 'B', 'b' && dest_city == 'C', 'c')
        transportation_price = 2500;

    else if(transportation_type == 'T', 't' && src_city == 'B', 'b' && dest_city == 'D', 'd')
        transportation_price = 2500;

    else if(transportation_type == 'T', 't' && src_city == 'B', 'b' && dest_city == 'M', 'm')
        transportation_price = 2000;

    else if(transportation_type == 'T', 't' && src_city == 'B', 'b' && dest_city == 'K', 'k')
        transportation_price = 2500;

    else if(transportation_type == 'T', 't' && src_city == 'B', 'b' && dest_city == 'C', 'c')
        transportation_price = 800;

    else if(transportation_type == 'B', 'b' && src_city == 'B', 'b' && dest_city == 'D', 'd')
        transportation_price = 2000;

    else if(transportation_type == 'B', 'b' && src_city == 'B', 'b' && dest_city == 'M', 'm')
        transportation_price = 1000;

    else if(transportation_type == 'B', 'b' && src_city == 'B', 'b' && dest_city == 'K', 'k')
        transportation_price = 2000;

    else if(transportation_type == 'B', 'b' && src_city == 'B', 'b' && dest_city == 'C', 'c')
        transportation_price = 2000;

    else if(transportation_type == 'A', 'a' && src_city == 'C', 'c' && dest_city == 'D', 'd')
        transportation_price = 2500;

    else if(transportation_type == 'A', 'a' && src_city == 'C', 'c' && dest_city == 'M', 'm')
        transportation_price = 4000;

    else if(transportation_type == 'A', 'a' && src_city == 'C', 'c' && dest_city == 'K', 'k')
        transportation_price = 4000;

    else if(transportation_type == 'A', 'a' && src_city == 'C', 'c' && dest_city == 'C', 'c')
        transportation_price = 6000;

    else if(transportation_type == 'T', 't' && src_city == 'C', 'c' && dest_city == 'D', 'd')
        transportation_price = 500;

    else if(transportation_type == 'T', 't' && src_city == 'C', 'c' && dest_city == 'M', 'm')
        transportation_price = 2300;

    else if(transportation_type == 'T', 't' && src_city == 'C', 'c' && dest_city == 'K', 'k')
        transportation_price = 1600;

    else if(transportation_type == 'T', 't' && src_city == 'C', 'c' && dest_city == 'C', 'c')
        transportation_price = 2000;

    else if(transportation_type == 'B', 'b' && src_city == 'C', 'c' && dest_city == 'D', 'd')
        transportation_price = 600;

    else if(transportation_type == 'B', 'b' && src_city == 'C', 'c' && dest_city == 'M', 'm')
        transportation_price = 1300;

    else if(transportation_type == 'B', 'b' && src_city == 'C', 'c' && dest_city == 'K', 'k')
        transportation_price = 1400;

    else if(transportation_type == 'B', 'b' && src_city == 'C', 'c' && dest_city == 'C', 'c')
        transportation_price = 1700;

    else if(transportation_type == 'A', 'a' && src_city == 'N', 'n' && dest_city == 'D', 'd')
        transportation_price = 5000;

    else if(transportation_type == 'A', 'a' && src_city == 'N', 'n' && dest_city == 'M', 'm')
        transportation_price = 2500;

    else if(transportation_type == 'A', 'a' && src_city == 'N', 'n' && dest_city == 'K', 'k')
        transportation_price = 4000;

    else if(transportation_type == 'A', 'a' && src_city == 'N', 'n' && dest_city == 'C', 'c')
        transportation_price = 4500;

    else if(transportation_type == 'T', 't' && src_city == 'N', 'n' && dest_city == 'D', 'd')
        transportation_price = 1500;

    else if(transportation_type == 'T', 't' && src_city == 'N', 'n' && dest_city == 'M', 'm')
        transportation_price = 900;

    else if(transportation_type == 'T', 't' && src_city == 'N', 'n' && dest_city == 'K', 'k')
        transportation_price = 1500;

    else if(transportation_type == 'T', 't' && src_city == 'N', 'n' && dest_city == 'C', 'c')
        transportation_price = 1700;

    else if(transportation_type == 'B', 'b' && src_city == 'N', 'n' && dest_city == 'D', 'd')
        transportation_price = 1400;

    else if(transportation_type == 'B', 'b' && src_city == 'N', 'n' && dest_city == 'M', 'm')
        transportation_price = 700;

    else if(transportation_type == 'B', 'b' && src_city == 'N', 'n' && dest_city == 'K', 'k')
        transportation_price = 1000;

    else if(transportation_type == 'B', 'b' && src_city == 'N', 'n' && dest_city == 'C', 'c')
        transportation_price = 1300;

    else if(transportation_type == 'A', 'a' && src_city == 'P', 'p' && dest_city == 'D', 'd')
        transportation_price = 5000;

    else if(transportation_type == 'A', 'a' && src_city == 'P', 'p' && dest_city == 'M', 'm')
        transportation_price = 4500;

    else if(transportation_type == 'A', 'a' && src_city == 'P', 'p' && dest_city == 'K', 'k')
        transportation_price = 3000;

    else if(transportation_type == 'A', 'a' && src_city == 'P', 'p' && dest_city == 'C', 'c')
        transportation_price = 4500;

    else if(transportation_type == 'T', 't' && src_city == 'P', 'p' && dest_city == 'D', 'd')
        transportation_price = 2000;

    else if(transportation_type == 'T', 't' && src_city == 'P', 'p' && dest_city == 'M', 'm')
        transportation_price = 1900;

    else if(transportation_type == 'T', 't' && src_city == 'P', 'p' && dest_city == 'K', 'k')
        transportation_price = 1200;

    else if(transportation_type == 'T', 't' && src_city == 'P', 'p' && dest_city == 'C', 'c')
        transportation_price = 1700;

    else if(transportation_type == 'B', 'b' && src_city == 'P', 'p' && dest_city == 'D', 'd')
        transportation_price = 1400;

    else if(transportation_type == 'B', 'b' && src_city == 'P', 'p' && dest_city == 'M', 'm')
        transportation_price = 1300;

    else if(transportation_type == 'B', 'b' && src_city == 'P', 'p' && dest_city == 'K', 'k')
        transportation_price = 800;

    else if(transportation_type == 'B', 'b' && src_city == 'P', 'p' && dest_city == 'C', 'c');
        transportation_price = 1300;

我用字符来表示每个城市和交通方式。这个if/else if语句不起作用，因为在我的输出中，不管用户输入什么，它给我的值都是$1300。

有没有办法缩短这段时间？或者如果我在什么地方搞砸了，有人能帮我指出吗？

如有任何帮助，我们不胜感激！

Answer 1

如前所述，仅使用大写选择或将选择转换为相同的大小写。此外，您可以将行程组合存储在数组中，以使代码更加整洁。

#include <stdio.h>
#include <math.h>

int main(){

    char transportation_type = 'A';
    char src_city = 'B';
    char dest_city = 'K';
    int transportation_price = 0;
          
    if(transportation_type == 'A' && src_city == 'B' && dest_city == 'D')
            transportation_price = 5000;
            
    else if(transportation_type == 'A' && src_city == 'B' && dest_city == 'M')
            transportation_price = 4000;
    
    else if(transportation_type == 'A' && src_city == 'B' && dest_city == 'K')
            transportation_price = 5000;
    
    printf("%i\n",transportation_price);
    
    
    // better way, store trip combinations in array
    
    char trips[4][3] = {
        {'A','B','D'},
        {'A','B','M'},
        {'A','B','K'},
        {'A','B','C'}
    };
    
    int cost[4] = {
        5000,4000,5000,2500
    };
    
    for (int t=0; t<3; t++) {
        if(transportation_type == trips[t][0] && src_city == trips[t][1] && dest_city == trips[t][2]) {
              transportation_price = cost[t];
              break;
        }
    }
    
    printf("%i\n",transportation_price);
    
    return transportation_price;
}

输出

5000
5000