Can I do this with LINQ?

Question

Can I do either of these using LINQ:

1. Check that each element in an IEnumerable<string> has the correct extension. If not, throw exception.

foreach(var filepath in filepaths)
    if(Path.GetExtension(filepath) != @".xml")
        throw new ArgumentException(...);

---

2. Take an IEnumerable<string> and serialise all of its elements into one string, with spaces in between each.

string args = "";
foreach (var filepath in filepaths)
    args += filepath + " ";

Thanks

Answer 1

if (!filepaths.All(x => Path.GetExtension(x) == @".xml"))
{
  throw error;
}

string.Join(" ", filepaths.ToArray()) for the second question.

Answer 2

1.

if(filePaths.Any(filepath => Path.GetExtension(filepath) != @".xml"))
     throw new ArgumentException(...);

2.

string args = string.Join(" ", filePaths.ToArray());

or, with LINQ (much more inefficient):

string args = filePaths.Aggregate("", (combined, path) => combined + " " + path);