Learn more about C #-optional parameters, and default values (chapter 1, 1.3 ),

Learn more about C #-optional parameters, and default values (chapter 1, 1.3 ),
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• C # null type
• C # optional parameters and default values

C # null type

In daily life, I believe that everyone cannot leave their cell phones! Haha... If the mobile phone manufacturer has produced a new mobile phone, which is not yet priced, what should we do in C #1?

Common solutions:

 1   public class Product 2     { 3         private string name; 4         private ProductPrice price; 5  6         public Product(string name, ProductPrice price) 7         { 8             this.name = name; 9             this.price = price;10         }11     }12     public class ProductPrice13     {14         public decimal Price;15         public bool HasPrice;16     }

The introduction of the void type in C #2 greatly simplifies the process.

 1 public class Product 2     { 3         public string Name { get; set; } 4         public decimal? Price { get; set; } 5         public Product(string name, decimal? price ) 6         { 7             this.Name = name; 8             this.Price = price; 9         }    10     }

C # optional parameters and default values

In our daily development, the same value is always transmitted for specific parameters when calling a method, while the traditional solution is to overload the method. Let's go back to the Product class mentioned in the previous article. If most of our products do not include the price, but optional parameters are introduced in C #4 to simplify this type of operation.

1 public class Product 2 {3 public string Name {get; set;} 5Public decimal? Price {get; set ;}7 public Product (string name,Decimal? Price = null) 8 {9 this. name = name; 10 this. price = price; 11} 12 public static List <Product> GetSampleProducts () 13 {14 List <Product> list = new List <Product> (); 15 list. add (New Product ("hard-mounted Furong Wang")); 16 list. add (new Product ("fine white sand", 9 m); 17 list. add (new Product ("soft white sand", 5.5 m); 18 return list; 19} 20 public override string ToString () 21 {22 return string. format ("{0 }:{ 1}", Name, Price); 23} 24}

Note:

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C # null type

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