在VS2013的C＃中更新列表中每个元素的值

Question

I need to update value in each element of a list in C# of VS2013.

The code:

var wl = myList.ToArray();
List<myElement> tl = new List<myElement>();
tl = givenList; // I need to update values in element in this list
for(int p =0; p < wl.Count(); ++p)
{
    decimal? fv = (wl[p].value * 10) / ((decimal?)a_constant);
    tl.ToArray()[p].value = fv; // this cannot update the value
}
myList = tl;

But, the tl.ToArray()[p].value = fv; does not update the value.

Any help would be appreciated.

Answer 1

You're creating a huge amount of variables which don't really do much, and is very hard to read. Also, you don't need to keep calling ToArray Try something like this:

for(int p = 0; p < myList.Count; ++p)
{
    decimal? fv = (myList[p].value * 10) / ((decimal?)a_constant);
    givenList[p].value = fv;
}

Answer 2

tl.ToArray() creates a copy of each element. I'm not sure what is the type of myElement in the code, but if it's a struct or any other value type that would explain why your collection is not being modified. Your code would update a copy of your element, not the element itself