I have some code that I would like to turn to linq - linq

Question

I have this piece of code where highAmtCtrList is a list of Outstanding contracts that have to be updated and comCtrList is a list of Dilution contracts from which I update highAmtCtrList.
So, for each conctract in highAmtCtrList, if I find a matching contract in comCtrList, I update it with the amount returned from comCtrList.
The code works, it's just that I would like to change it to linq.
Any ideas.
tks in advance.
Rui Martins
foreach (Outstanding outCtr in highAmtCtrList)
{
Dilution dilCtr =
comCtrList.FirstOrDefault(dil => dil.Contract == outCtr.Contract);
if (dilCtr != null) outCtr.Amount += dilCtr.Amount;
}

Answer 1

Your code looks fine. You can write all this in one line, but IMO it's a less maintainable code:
outCtr.Join(comCtrList,
o => o.Contract,
i => i.Contract,
(o, i) => o.Amount += i.Amount);
EDIT: to sum only first matches:
outCtr.ForEach(o => o.Amount += comCtrList
.Where(i => i.Contract == o.Contract)
.Select(i => i.Amount)
.FirstOrDefault());

Answer 2

How about this?
foreach (Outstanding o in highAmtCtrList)
{
o.Amount += comCtrList.Where(d => d.Contract == o.Contract)
.Select(d => d.Amount)
.FirstOrDefault();
}
Here's another alternative:
foreach (Outstanding o in highAmtCtrList)
{
o.Amount += comCtrList.Where(d => d.Contract == o.Contract)
.Take(1)
.Sum(d => d.Amount);
}