c# regex match
const string input = "Lorem ipsum dolor sit %download%#456 amet, consectetur adipiscing %download%#3434 elit. Duis non nunc nec mauris feugiat porttitor. Sed tincidunt blandit dui a viverra%download%#298. Aenean dapibus nisl %download%#893434 id nibh auctor vel tempor velit blandit.";
static void Main(string[] args)
{
Regex expression = new Regex(@"%download%#(?<Identifier>[0-9]*)");
var results = expression.Matches(input);
foreach (Match match in results)
{
Console.WriteLine(match.Groups["Identifier"].Value);
}
}