從一個簡單的超市收銀系統(tǒng)，我們來練習(xí)一個系統(tǒng)如何設(shè)計，然后如何實現(xiàn)的思路。

在Ubuntu環(huán)境下使用C語言編寫一個簡單的超市收銀系統(tǒng)。以下是一個基本的示例，涵蓋了商品管理、購物車、交易處理等功能。

代碼

#include <stdio.h>
#include <stdlib.h>// 商品結(jié)構(gòu)體
struct Product {int id;char name[50];float price;
};// 購物車項結(jié)構(gòu)體
struct ShoppingCartItem {struct Product product;int quantity;
};// 交易結(jié)構(gòu)體
struct Transaction {struct ShoppingCartItem *items;int itemCount;
};// 商品管理結(jié)構(gòu)體
struct Inventory {struct Product *products;int productCount;
};// 初始化商品管理系統(tǒng)
struct Inventory initializeInventory() {struct Inventory inventory;inventory.products = NULL;inventory.productCount = 0;return inventory;
}// 添加商品到庫存
void addProduct(struct Inventory *inventory, struct Product product) {inventory->products = realloc(inventory->products, (inventory->productCount + 1) * sizeof(struct Product));inventory->products[inventory->productCount++] = product;
}// 顯示庫存信息
void displayInventory(struct Inventory inventory) {printf("Inventory:\n");for (int i = 0; i < inventory.productCount; ++i) {printf("%d. %s - $%.2f\n", inventory.products[i].id, inventory.products[i].name, inventory.products[i].price);}
}// 獲取商品信息
struct Product getProductInfo(struct Inventory inventory, int productId) {for (int i = 0; i < inventory.productCount; ++i) {if (inventory.products[i].id == productId) {return inventory.products[i];}}struct Product notFound;notFound.id = -1;return notFound;
}// 初始化交易
struct Transaction initializeTransaction() {struct Transaction transaction;transaction.items = NULL;transaction.itemCount = 0;return transaction;
}// 添加商品到購物車
void addToCart(struct Transaction *transaction, struct Product product, int quantity) {transaction->items = realloc(transaction->items, (transaction->itemCount + 1) * sizeof(struct ShoppingCartItem));transaction->items[transaction->itemCount].product = product;transaction->items[transaction->itemCount].quantity = quantity;++transaction->itemCount;printf("Added %d %s(s) to the cart.\n", quantity, product.name);
}// 顯示購物車
void displayCart(struct Transaction transaction) {float total = 0.0;printf("Shopping Cart:\n");for (int i = 0; i < transaction.itemCount; ++i) {struct ShoppingCartItem item = transaction.items[i];printf("%s - Quantity: %d\n", item.product.name, item.quantity);total += item.product.price * item.quantity;}printf("Total Price: $%.2f\n", total);
}// 完成交易
void completeTransaction(struct Transaction transaction) {printf("Transaction completed. Thank you!\n");free(transaction.items);
}int main() {struct Inventory inventory = initializeInventory();// 添加一些商品addProduct(&inventory, (struct Product){1, "Milk", 2.5});addProduct(&inventory, (struct Product){2, "Bread", 1.0});addProduct(&inventory, (struct Product){3, "Eggs", 3.0});struct Transaction transaction = initializeTransaction();// 超市收銀系統(tǒng)while (1) {displayInventory(inventory);int productId;printf("Enter product ID to add to cart (or 0 to finish): ");scanf("%d", &productId);if (productId == 0) {break;}struct Product product = getProductInfo(inventory, productId);if (product.id != -1) {int quantity;printf("Enter quantity: ");scanf("%d", &quantity);addToCart(&transaction, product, quantity);} else {printf("Product not found.\n");}}displayCart(transaction);completeTransaction(transaction);// 釋放資源free(inventory.products);return 0;
}

編譯：

gcc supermarket.c -o supermarket
./supermarket

程序設(shè)計的詳細(xì)過程：

步驟 1: 定義數(shù)據(jù)模型

在程序設(shè)計的起始階段，定義了程序需要用到的數(shù)據(jù)模型，包括商品、購物車項和交易。使用結(jié)構(gòu)體表示這些概念，其中包括商品（Product）、購物車項（ShoppingCartItem）和交易（Transaction）。

struct Product {int id;char name[50];float price;
};struct ShoppingCartItem {struct Product product;int quantity;
};struct Transaction {struct ShoppingCartItem *items;int itemCount;
};

步驟 2: 商品管理

設(shè)計商品管理系統(tǒng)，包括添加商品到庫存和獲取商品信息的功能。使用結(jié)構(gòu)體 Inventory 來保存商品信息，并定義相應(yīng)的函數(shù)。

struct Inventory {struct Product *products;int productCount;
};// 添加商品到庫存
void addProduct(struct Inventory *inventory, struct Product product) {// 通過realloc動態(tài)分配內(nèi)存以保存商品inventory->products = realloc(inventory->products, (inventory->productCount + 1) * sizeof(struct Product));inventory->products[inventory->productCount++] = product;
}// 獲取商品信息
struct Product getProductInfo(struct Inventory inventory, int productId) {for (int i = 0; i < inventory.productCount; ++i) {if (inventory.products[i].id == productId) {return inventory.products[i];}}struct Product notFound;notFound.id = -1;return notFound;
}

步驟 3: 用戶界面

設(shè)計用戶界面，實現(xiàn)基本的用戶交互，允許用戶選擇商品并添加到購物車。使用結(jié)構(gòu)體 CashierUI 和相應(yīng)的函數(shù)。

struct CashierUI {struct Inventory inventory;struct Transaction transaction;
};// 顯示庫存信息
void displayInventory(struct Inventory inventory) {// 輸出商品列表
}// 添加商品到購物車
void addToCart(struct Transaction *transaction, struct Product product, int quantity) {// 將商品添加到購物車
}// 顯示購物車信息
void displayCart(struct Transaction transaction) {// 輸出購物車內(nèi)容
}// 完成交易
void completeTransaction(struct Transaction transaction) {// 輸出總價和完成交易信息
}

步驟 4: 交易處理

實現(xiàn)交易處理功能，計算購物車中商品的總價并完成交易。

// 初始化交易
struct Transaction initializeTransaction() {struct Transaction transaction;transaction.items = NULL;transaction.itemCount = 0;return transaction;
}// 完成交易
void completeTransaction(struct Transaction transaction) {// 輸出總價和完成交易信息// 釋放購物車內(nèi)存free(transaction.items);
}

步驟 5: 主程序

在主程序中，創(chuàng)建超市收銀系統(tǒng)實例，添加一些商品，然后啟動收銀系統(tǒng)。

int main() {// 初始化商品管理系統(tǒng)struct Inventory inventory = initializeInventory();// 添加一些商品addProduct(&inventory, (struct Product){1, "Milk", 2.5});addProduct(&inventory, (struct Product){2, "Bread", 1.0});addProduct(&inventory, (struct Product){3, "Eggs", 3.0});// 初始化交易struct Transaction transaction = initializeTransaction();// 超市收銀系統(tǒng)while (1) {// 顯示庫存信息displayInventory(inventory);int productId;printf("Enter product ID to add to cart (or 0 to finish): ");scanf("%d", &productId);if (productId == 0) {break;}// 獲取商品信息struct Product product = getProductInfo(inventory, productId);if (product.id != -1) {int quantity;printf("Enter quantity: ");scanf("%d", &quantity);// 添加商品到購物車addToCart(&transaction, product, quantity);} else {printf("Product not found.\n");}}// 顯示購物車displayCart(transaction);// 完成交易completeTransaction(transaction);// 釋放資源free(inventory.products);return 0;
}

這個設(shè)計過程包括了程序的整體結(jié)構(gòu)、數(shù)據(jù)模型的定義、功能的實現(xiàn)以及用戶界面的設(shè)計。當(dāng)設(shè)計一個更大規(guī)模的系統(tǒng)時，可能需要考慮更多的功能，例如支付處理、庫存管理、用戶認(rèn)證等。這個簡化的例子提供了一個基本的框架，可以根據(jù)實際需求進行擴展。