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5.1.5 Creating Filtering Extension Methods

chap5
Jason Zhu 2021-07-12 12:15:56 +10:00
parent ec983ff21c
commit 61cf1cbfaf
1 changed files with 23 additions and 19 deletions
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38
chap5_essential_language_features/essential_csharp_features/Program.cs
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@ -14,28 +14,20 @@ namespace automatically_implemented_properties
{ {
Products = new List<Product> Products = new List<Product>
{ {
new Product {Name = "Kayak", Price = 275M}, new Product {Name = "Kayak", Category = "Watersports", Price = 275M},
new Product {Name = "Lifejacket", Price = 48.95M}, new Product {Name = "Lifejacket", Category = "Watersports", Price = 48.95M},
new Product {Name = "Soccer ball", Price = 19.50M}, new Product {Name = "Soccer ball", Category = "Soccer", Price = 19.50M},
new Product {Name = "Corner flag", Price = 34.95M} new Product {Name = "Corner flag", Category = "Soccer", Price = 34.95M}
} }
}; };
// create and populate an array of Product objects, implementing IEnumerable<Product> interface foreach (Product prod in products.FilterByCategory("Soccer"))
Product[] productArray =
{ {
new Product {Name = "Kayak", Price = 275M}, Console.WriteLine("Name: {0}, Price {1:c}", prod.Name, prod.Price);
new Product {Name = "Lifejacket", Price = 48.95M}, }
new Product {Name = "Soccer ball", Price = 19.50M},
new Product {Name = "Corner flag", Price = 34.95M}
};
// get total value of the products in cart decimal total = products.FilterByCategory("Soccer").TotalPrices();
decimal cartTotal = products.TotalPrices(); Console.WriteLine("Filtered total: {0:c}", total);
decimal arrayTotal = productArray.TotalPrices();
Console.WriteLine("Total: {0:c}", cartTotal);
Console.WriteLine("Array Total: {0:c}", arrayTotal);
} }
} }
@ -51,5 +43,17 @@ namespace automatically_implemented_properties
} }
return total; return total;
} }
public static IEnumerable<Product> FilterByCategory(this IEnumerable<Product> productEnum,
string categoryParam)
{
foreach (Product prod in productEnum)
{
if (prod.Category == categoryParam)
{
yield return prod;
}
}
}
} }
} }