Barefoot learning LINQ (011): perform operations on Source Elements

Http://u.115.com/file/f2ce0eeb6 demo

The output sequence may not contain any element or element attribute of the source sequence. The output may be a sequence of values calculated by using the source element as an input parameter. When executing the following simple query, this query will output a string sequence, which indicates the calculation based on the source sequence of the double type element.
Description
If a query is converted to another domain, you cannot call a method in a query expression. For example, you cannot call a general C # method in LINQ to SQL, because SQL server does not have the context of this method. However, you can map stored procedures to methods and then call methods.

// Data source.   double[] Radii = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };     // Results.   IEnumerable<string> Results =       from Rad in Radii       select String.Format("Area = {0}", (Rad * Rad) * 3.14);     // Results execution.    foreach (string Result in Results)       Console.WriteLine(Result);     // Keep the console open in debug mode.   Console.WriteLine("Press any key to exit.");   Console.ReadKey()  // Data source.double[] Radii = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };// Results.IEnumerable<string> Results =    from Rad in Radii    select String.Format("Area = {0}", (Rad * Rad) * 3.14);// Results execution. foreach (string Result in Results)    Console.WriteLine(Result);// Keep the console open in debug mode.Console.WriteLine("Press any key to exit.");Console.ReadKey() 

The output is as follows:

Area = 3.14   Area = 12.56   Area = 28.26   Area = 50.24   Area = 78.5   Area = 113.04   Area = 153.86   Area = 200.96   Area = 254.34