Lambda expression conversion

Question

I am a beginner in Linq.

How can I rewrite this lambda expression as a linq compiled query?

var query5 = CustomerList.Select((cust, index) =>  new {cust, index})
                         .Where(c =>  c.cust.Country == "USA"  &&  c.index  >  70)
                         .Select(c =>  new { c.cust.CustomerID, c.cust.CompanyName, 
                                            c.index });

like

var query5 = from c in .......
             where .....
             select c new {....}

That's not a "compiled" query. It's just a different syntax. It doesn't have a technical advantage. — Mehrdad Afshari
– Mehrdad Afshari, Commented Oct 13, 2009 at 7:23
I do feel the Linq syntax is more readable than the lambda variant. — Jonathan van de Veen
– Jonathan van de Veen, Commented Oct 13, 2009 at 7:29
@Jonathan van de Veen - maybe, but there are quite a few operations that are only available via the lambda syntax. — Graham Clark
– Graham Clark, Commented Oct 13, 2009 at 7:37

Jon Skeet · Accepted Answer · 2009-10-13 08:02:01Z

5

Well here's the closest query expression syntax:

var query5 = from c in CustomerList.Select((cust, index) =>  new {cust, index})
             where c.cust.Country == "USA"  &&  c.index  >  70
             select new { c.cust.CustomerID, c.cust.CompanyName, c.index };

Basically the one bit you can't do in query expression syntax is the "select including the index" overload. There simply isn't any syntax which translates to that. (The same goes for quite a few other operations - VB's LINQ syntax is richer in this respect, although personally I'm happy with the way that C# does it; it avoids adding too many contextual keywords.)

(As Mehrdad says, this isn't a "compiled" query. In fact the code will be compiled to exactly the same IL.)

edited Oct 13, 2009 at 8:02

answered Oct 13, 2009 at 7:23

Jon Skeet

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1 Comment

Yannick Motton Over a year ago

Wasn't aware of an overload that includes an index. Yet another linq mystery resolved :-D

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