, .
var posNums = from n in nums where n > 0 select n;
int len = posNums.Count(); //
Count () . .
, , Array () ToList (). Enumerable. ToAtray () , ToList () List. ( 25.) . , , posNums, .
int[] pnums = posNum.ToArray(); //
Foreach(int i in pnums)
Console.Write(i + " ");
}
, LINQ, , - . , -
, . System. Linq. Expressions. Expression<TDelegate>. , , SQL . , , . , , LINQ to SQL Visual Studio. , C# .
Compile (), Expression. , . Func System. Func , .
: -. -.
, . , , , . . , .
// .
Using System;
Using System.Linq;
|
|
Using System.Linq.Expressions;
class SimpleExpTree { static void Main() {
// - .
Expression<Func<int, int, bool
IsFactorExp = (n, d) => (d!= 0)? (n % d) ==0: false;
// .
Func<int, int, bool> IsFactor = IsFactorExp.Compile ();
// , if(IsFactor(10, 5))
Console.WriteLine(" 5 10.");
if(!IsFactor(10, 7))
Console.WriteLine(" 7 10.");
Console.WriteLine ();
}
}
.
5 10.
7 10.
. .
Expression<Func<int, int, bool
IsFactorExp = (n, d) => (d!= 0)? (n % d) ==0: false;
- . , , IsFactorExp. .
Func<int, int, bool> IsFactor = IsFactorExp.Compile();