替换struct c#数组中的值

Question

I have the following public struct in C#:

public struct Route
{
    public float Start; 
    public float End; 
    public float Range; 
    public bool InConstruction; 
};

I want to replace every property Range of Route used as an array of struct in an other class (Route[]). I did the following which works fine:

//dest.Route = new Route[]; 
for (var i = 0; i < dest.Route.Count; i++)
{
    dest.Route[i].Range = dest.Route[i].End - dest.Route[i].Start; 
}

Is there a way to optimize this loop or just other ways to implement this solution?

Maybe with desc.Route.Select(i => i.Range = i.End - i.Start); ?

Answer 1

If you can't change the struct, then no, you've done the most optimal thing. Even if you do find some solution with Linq, it's eventually just going to boil down to a loop like you have.

If you're dead set on using Linq, you'd need to do something like this:

desc.Route = desc.Route.Select(d => {
    d.Range = d.End - d.Start;
    return d;
})
.ToArray();

I'll let you be the judge if that's "better" for your project or not. This does go against some of the principles of Linq, mostly the "don't cause side effects".

This:

.Select(i => i.Range = i.End - i.Start)

Doesn't work (though it is legal syntax) because the assignment operator returns the value that was assigned, so you'd be selecting just the float assigned to the Range property , not the full Route object. https://dotnetfiddle.net/jSKZlj

---

If you can change the struct:

If Range is always the End field minus the Start field, then you could just compute it when you need to read the value , rather than preemptively. Shamelessly taking Etienne de Martel's idea :

public struct Route
{
    public float Start; 
    public float End; 
    public float Range => End - Start;
    public bool InConstruction; 
};

Now there's no need to do the loop calculation at all. The value for each object will be calculated as soon as you read the Range property.