Linq Queries converting to lambda expressions ?

Question

from item in range where item % 2 ==0 select i ;

extension methods equivelant of it is.

range.where(item % 2 ==0).select(x=>x).

I feel that first way of linq is translating next one by compiler and if it is,so is there any optimization by compiler like this range.where(item & 2 == 0) instead of other one ?

All of above queries are returning same results if you write it manually. But compiler does not have an idea about what is inside the select method. so it will not optimise up to that level. — Chamika Sandamal
– Chamika Sandamal, Commented Apr 2, 2013 at 5:46

JaredPar · Accepted Answer · 2010-06-08 14:39:18Z

2

No the C# compiler will not ever remove the .Select call at the end of the LINQ query. The reason why is that the C# compiler has no knowledge of what the .Select method does and hence cannot remove it as an optimization.

The compiler cannot have this knowledge because it binds to Select in a very flexible way. It will consider any instance or extension method named Select on the target type which has the appropriate signature. You can even define your own Select methods to do customized actions like logging. If the C# compiler removed the Select clause in this case it would break this type of code.

answered Jun 8, 2010 at 14:39

JaredPar

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3 Comments

Freshblood Over a year ago

all these queries which i wrote has same result ?

JaredPar Over a year ago

@Freshblood, I don't understand what you mean by that

Freshblood Over a year ago

Yes, these three query produce same result that was what i asked.

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