Question

It’s a simple question but i don’t really know how to do it efficiently. Is there any way to efficiently convert list of values to array e.g List<int> to int[] OR List<CustomObj> to CustomObj[] directly without using loops preferably by using Linq?

In addition, I have a GenericCollection<T>, how can i convert the Linq query to GenericCollection<T> directly without looping e.g.

GenericCollection<T> result = SomeGenericCollection.Select(o => o).ToList<GenericCollection<T>>();

Answer 1

for the first part of your question, look at the ToArray() method as per the other answers:

• List<T>.ToArray(): http://msdn.microsoft.com/en-us/library/x303t819.aspx
• Enumerable.ToArray<T>() extension method: http://msdn.microsoft.com/en-us/library/x303t819.aspx#Y0

For the second part, you can write your own extension method:

public static class MyExtensions
{
   public static GenericCollection<T> ToGenericCollection<T>(
     this IEnumerable<T> input
   )
   {
      // write the conversion here - typically you will need a for loop
   }
}

Once you have this, you can convert any collection to your GenericCollection<T> as follows:

var result = SomeGenericCollection.Select(o => o).ToGenericCollection();

You really can’t avoid having to write the loop, but this way you only have to write it once.