Question

I have this code

Dim sum As Integer = scores.Sum(Function(score) score.Fraction * score.Score)
Dim count As Integer = scores.Sum(Function(score) score.Fraction)

or in C#:

var sum=scores.Sum(score=>score.Fraction * score.Score);
var count=scores.Sum(score=>score.Fraction);

How can I merge these AND achieve that the collection is only enumerated once? I did find some examples but if I am not mistaken they still iterate the collection twice.

Answer 1

var sum = 0;
var count = 0;

foreach(var score in scores){
    sum += score.Fraction * score.Score;
    count += score.Fraction;
}

… My point is, why use LINQ at all – it’s meant to make certain things easier, but this is not easier with LINQ.