LINQ：用匿名类型处理

Question

我试图生成表单的图表：

User A User B  Owes  Owed  Net 
Sam  David  $20  $10  $10 
Timbo  ODP  $30  $0  $30 

使用下面的查询：

 var debt = from user in users 
        select new { 
        Username = username, 
        User = user, 
        Owes = owedBetween(username, user), 
        Owed = owedBetween(user, username), 
        Net = Owes - Owed // doesn't compile 
        }; 

的问题是，最后行不编译。有没有办法在查询中设置Net值，还是必须将其初始化为零，然后再进行更改？

Answer 1

尝试使用let关键字：

var debt = from user in users 
       let owes = owedBetween(username, user) 
       let owed = owedBetween(user, username) 
       select new { 
       Username = username, 
       User = user, 
       Owes = owes, 
       Owed = owed, 
       Net = owes - owed 
       }; 

Answer 2

尝试：

Net = owedBetween(username, user) - owedBetween(user, username) 

顺便说一句，我建议你用更好的名称为username和user。哪个是哪个？