如何在C语言点餐程序中输出用户选择的所有商品列表？

需求说明 #

我编写的C语言点餐程序目前可计算用户所选商品的总费用，但需要在显示总费用前，列出用户选择的所有商品。

现有代码 #

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

struct menuDetails {
    double total, priceA, priceB, priceC, priceD, priceE, priceF;
} md;

int main()
{
    int itemTotal, itemName, itemAll;
    int sum=0;
    char item;
    char itemA[10]= "Nasi Ayam";
    char itemB[20]= "Nasi Ayam Merah";
    char itemC[15]= "Nasi Kerabu";
    char itemD[10]= "Sotong";
    char itemE[10]= "Teh Peng";
    char itemF[5]= "Kopi";

    printf("\t========= Menu =========\n");
    printf("Item \t Name \t\t\t Price (RM)\n");
    printf("A \t Nasi Ayam \t\t 3.50\n");
    printf("B \t Nasi Ayam Merah \t 4.00\n");
    printf("C \t Nasi Kerabu \t\t 5.50\n");
    printf("D \t Sotong \t\t 2.00\n");
    printf("E \t Teh Peng \t\t 2.00\n");
    printf("F \t Kopi \t\t\t 2.00\n");
    
    printf("\nHow many items would you like to purchase: ");
    scanf("%d", &itemTotal);
    printf("You have chose to order %d items\n\n", itemTotal);
    
    for(itemName = 1; itemName <= itemTotal; itemName++)
    {
        printf("Item %d [Enter Item (A-F)]: ", itemName);
        scanf(" %c", &item);
        
        md.priceA = 3.50;
        md.priceB = 4.00;
        md.priceC = 5.50;
        md.priceD = 2.00;
        md.priceE = 2.00;
        md.priceF = 2.00;
        
        if (item == 'A' || item == 'a') {
            printf("%s = RM%.2f\n\n", itemA, md.priceA);
            md.total = md.total + md.priceA;
        }else if (item == 'B' || item == 'b') {
            printf("%s = RM%.2f\n\n", itemB, md.priceB);
            md.total = md.total + md.priceB;
        }else if (item == 'C' || item == 'c') {
            printf("%s = RM%.2f\n\n", itemC, md.priceC);
            md.total = md.total + md.priceC;
        }else if (item == 'D' || item == 'd') {
            printf("%s = RM%.2f\n\n", itemD, md.priceD);
            md.total = md.total + md.priceD;
        }else if (item == 'E' || item == 'e') {
            printf("%s = RM%.2f\n\n", itemE, md.priceE);
            md.total = md.total + md.priceE;
        }else if (item == 'F' || item == 'f') {
            printf("%s = RM%.2f\n\n", itemF, md.priceF);
            md.total = md.total + md.priceF;            
        }
    } 
    printf("The total is RM%.2f", md.total);
    
    time_t my_time = time(NULL);
    printf("\nDate: %s", ctime(&my_time));
    
    return 0;
}

当前输出 #

========= Menu =========
Item     Name                    Price (RM)
A        Nasi Ayam               3.50
B        Nasi Ayam Merah         4.00
C        Nasi Kerabu             5.50
D        Sotong                  2.00
E        Teh Peng                2.00
F        Kopi                    2.00

How many items would you like to purchase: 3
You have chose to order 3 items

Item 1 [Enter Item (A-F)]: a
Nasi Ayam = RM3.50

Item 2 [Enter Item (A-F)]: b
Nasi Ayam Merah = RM4.00

Item 3 [Enter Item (A-F)]: c
Nasi Kerabu = RM5.50

The total is RM13.00
Date: Thu Dec 29 17:02:49 2022

期望输出 #

========= Menu =========
Item     Name                    Price (RM)
A        Nasi Ayam               3.50
B        Nasi Ayam Merah         4.00
C        Nasi Kerabu             5.50
D        Sotong                  2.00
E        Teh Peng                2.00
F        Kopi                    2.00

How many items would you like to purchase: 3
You have chose to order 3 items

Item 1 [Enter Item (A-F)]: a
Nasi Ayam = RM3.50

Item 2 [Enter Item (A-F)]: b
Nasi Ayam Merah = RM4.00

Item 3 [Enter Item (A-F)]: c
Nasi Kerabu = RM5.50

Receipt:
Nasi Ayam
Nasi Ayam Merah
Nasi Kerabu

The total is RM13.00
Date: Thu Dec 29 17:02:49 2022

修改后的代码 #

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>

struct menuDetails {
    double total, priceA, priceB, priceC, priceD, priceE, priceF;
} md;

int main()
{
    int itemTotal, itemName, itemAll;
    int sum=0;
    char item;
    char itemA[10]= "Nasi Ayam";
    char itemB[20]= "Nasi Ayam Merah";
    char itemC[15]= "Nasi Kerabu";
    char itemD[10]= "Sotong";
    char itemE[10]= "Teh Peng";
    char itemF[5]= "Kopi";
    // 存储已选商品名称的动态数组
    char** selectedItems = NULL;

    printf("\t========= Menu =========\n");
    printf("Item \t Name \t\t\t Price (RM)\n");
    printf("A \t Nasi Ayam \t\t 3.50\n");
    printf("B \t Nasi Ayam Merah \t 4.00\n");
    printf("C \t Nasi Kerabu \t\t 5.50\n");
    printf("D \t Sotong \t\t 2.00\n");
    printf("E \t Teh Peng \t\t 2.00\n");
    printf("F \t Kopi \t\t\t 2.00\n");
    
    printf("\nHow many items would you like to purchase: ");
    scanf("%d", &itemTotal);
    printf("You have chose to order %d items\n\n", itemTotal);

    // 为数组分配内存
    selectedItems = (char**)malloc(itemTotal * sizeof(char*));
    
    for(itemName = 0; itemName < itemTotal; itemName++)
    {
        printf("Item %d [Enter Item (A-F)]: ", itemName + 1);
        scanf(" %c", &item);
        
        md.priceA = 3.50;
        md.priceB = 4.00;
        md.priceC = 5.50;
        md.priceD = 2.00;
        md.priceE = 2.00;
        md.priceF = 2.00;
        
        if (item == 'A' || item == 'a') {
            printf("%s = RM%.2f\n\n", itemA, md.priceA);
            md.total = md.total + md.priceA;
            selectedItems[itemName] = (char*)malloc(strlen(itemA) + 1);
            strcpy(selectedItems[itemName], itemA);
        }else if (item == 'B' || item == 'b') {
            printf("%s = RM%.2f\n\n", itemB, md.priceB);
            md.total = md.total + md.priceB;
            selectedItems[itemName] = (char*)malloc(strlen(itemB) + 1);
            strcpy(selectedItems[itemName], itemB);
        }else if (item == 'C' || item == 'c') {
            printf("%s = RM%.2f\n\n", itemC, md.priceC);
            md.total = md.total + md.priceC;
            selectedItems[itemName] = (char*)malloc(strlen(itemC) + 1);
            strcpy(selectedItems[itemName], itemC);
        }else if (item == 'D' || item == 'd') {
            printf("%s = RM%.2f\n\n", itemD, md.priceD);
            md.total = md.total + md.priceD;
            selectedItems[itemName] = (char*)malloc(strlen(itemD) + 1);
            strcpy(selectedItems[itemName], itemD);
        }else if (item == 'E' || item == 'e') {
            printf("%s = RM%.2f\n\n", itemE, md.priceE);
            md.total = md.total + md.priceE;
            selectedItems[itemName] = (char*)malloc(strlen(itemE) + 1);
            strcpy(selectedItems[itemName], itemE);
        }else if (item == 'F' || item == 'f') {
            printf("%s = RM%.2f\n\n", itemF, md.priceF);
            md.total = md.total + md.priceF;
            selectedItems[itemName] = (char*)malloc(strlen(itemF) + 1);
            strcpy(selectedItems[itemName], itemF);            
        }
    } 

    // 打印已选商品清单
    printf("Receipt:\n");
    for(itemName = 0; itemName < itemTotal; itemName++){
        printf("%s\n", selectedItems[itemName]);
        free(selectedItems[itemName]);
    }
    free(selectedItems);
    printf("\n");

    printf("The total is RM%.2f", md.total);
    
    time_t my_time = time(NULL);
    printf("\nDate: %s", ctime(&my_time));
    
    return 0;
}

修改说明 #

1. 新增char** selectedItems动态数组，根据用户输入的商品数量分配内存，用于存储已选商品名称
2. 在每个商品选择分支中，为当前商品名称分配内存并复制到数组中
3. 在输出总费用前，遍历数组打印所有已选商品，同时释放分配的内存避免泄漏
4. 调整循环索引为0起始，打印序号时用itemName + 1保持原有显示逻辑

内容的提问来源于stack exchange，提问作者Nozakai