.NET 4.0 Generics

Time for action – checking whether there is only one item matching this pattern

Follow the given steps:

1. Copy the following as a query to LINQPad:

   string[] names = { "Sam", "Danny", "Jeff", "Erik", "Anders" };
   string onlyOne = names.Single(c => c.StartsWith("Dan"));
   onlyOne.Dump("Only name with Dan*");

2. Run the query and you should get the following output:
   

What just happened?

This will have "Danny" stored in onlyOne as that's the only name in the sequence names that starts with "Dan". However, the following snippet will throw an exception as there is more than one element in the source collection:

try { string w = names.Single();//This line will throw ...