向购物车添加商品
本课属于 Coddy Dart 学习旅程的“逻辑与流程控制”单元。第 34 课，共 65 课。
挑战
简单创建一个程序，实现将商品添加到购物车的功能。程序应使用硬编码的商品目录 Map 和一个空的购物车 List，然后处理用户输入的商品。
在代码中直接定义以下商品目录：
Map<String, double> productCatalog = {
'Apple': 1.50,
'Banana': 0.80,
'Orange': 2.00,
'Milk': 3.25,
'Laptop': 999.99,
'Mouse': 25.50,
'Keyboard': 75.00,
'Novel': 12.99,
'Magazine': 4.50,
'Textbook': 89.00
};你的程序应：
- 使用上面定义的商品目录 Map 和一个空的购物车 List
- 读取多个表示顾客想要添加到购物车的字符串输入（收到
"cart_done"时，输入结束） - 对于每件商品，使用
containsKey()检查它是否存在于商品目录中 - 如果商品存在，使用
add()方法将其添加到购物车 List 中 - 如果商品不存在，则跳过它并继续处理
- 跟踪成功添加的次数和失败的尝试次数
- 按照下方所示的确切格式显示购物车管理报告
例如，如果顾客想添加 "Apple"、"Bread"、"Banana"、"Apple"、"Juice"，你的程序应输出：
Shopping Cart Operations:
Adding 'Apple': Item added to cart successfully
Adding 'Bread': Item not available in store
Adding 'Banana': Item added to cart successfully
Adding 'Apple': Item added to cart successfully
Adding 'Juice': Item not available in store
Cart Contents: [Apple, Banana, Apple]
Cart Summary:
Total items in cart: 3
Unique products in cart: 2
Items successfully added: 3
Items not found: 2
Cart Status: Ready for checkout如果顾客想添加 "Mouse"、"Monitor"、"Keyboard"、"Mouse"，你的程序应输出：
Shopping Cart Operations:
Adding 'Mouse': Item added to cart successfully
Adding 'Monitor': Item not available in store
Adding 'Keyboard': Item added to cart successfully
Adding 'Mouse': Item added to cart successfully
Cart Contents: [Mouse, Keyboard, Mouse]
Cart Summary:
Total items in cart: 3
Unique products in cart: 2
Items successfully added: 3
Items not found: 1
Cart Status: Ready for checkout如果顾客想添加 "Novel"、"Dictionary"、"Magazine"、"Novel"、"Comic"、"Textbook"，你的程序应输出：
Shopping Cart Operations:
Adding 'Novel': Item added to cart successfully
Adding 'Dictionary': Item not available in store
Adding 'Magazine': Item added to cart successfully
Adding 'Novel': Item added to cart successfully
Adding 'Comic': Item not available in store
Adding 'Textbook': Item added to cart successfully
Cart Contents: [Novel, Magazine, Novel, Textbook]
Cart Summary:
Total items in cart: 4
Unique products in cart: 3
Items successfully added: 4
Items not found: 2
Cart Status: Ready for checkout你的程序必须使用 containsKey()，在将每件商品添加到购物车之前，验证它是否存在于商品目录中。使用 add() 方法将有效商品追加到购物车 List 中。使用 length 属性统计购物车中的商品总数，并将购物车转换为 Set，通过检查其 length 确定不重复商品的数量。跟踪成功添加的次数，以及商品目录中未找到的商品数量。输入格式为：要添加到购物车的商品名称，最后以 "cart_done" 结束。
亲手试试
import 'dart:io';
void main() {
// Read store name
String? storeName = stdin.readLineSync();
// Initialize data structures
Map<String, double> products = {};
List<String> shoppingCart = [];
// Read products until "products_done"
while (true) {
String? input = stdin.readLineSync();
if (input == "products_done") {
break;
}
String productName = input!;
String? priceInput = stdin.readLineSync();
double price = double.parse(priceInput!);
// Add product to map
products[productName] = price;
}
// Calculate statistics
double totalPrice = 0;
double maxPrice = 0;
double minPrice = double.infinity;
String mostExpensiveItem = '';
String cheapestItem = '';
for (String productName in products.keys) {
double price = products[productName]!;
totalPrice += price;
if (price > maxPrice) {
maxPrice = price;
mostExpensiveItem = productName;
}
if (price < minPrice) {
minPrice = price;
cheapestItem = productName;
}
}
double averagePrice = totalPrice / products.length;
// Print the store setup report
print('Store: $storeName');
print('Product Catalog Setup:');
print('Available Products: $products');
print('Shopping Cart Initialized: $shoppingCart');
print('System Status:');
print('Total products available: ${products.length}');
print('Cart status: Empty');
print('Most expensive item: $mostExpensiveItem (\$${maxPrice.toStringAsFixed(2)})');
print('Cheapest item: $cheapestItem (\$${minPrice.toStringAsFixed(2)})');
print('Average product price: \$${averagePrice.toStringAsFixed(2)}');
print('Setup Status: Shopping cart system ready for customers');
}逻辑与流程控制中的所有课
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