How do i exit a List.ForEach loop when using an anonymous delegate?

Question

In a normal loop you can break out of a loop using break. Can the same be done using an anonymous delegate?

Example inputString and result are both declared outside

Answer 1

Would this work for you:

bool result = null != blackList.Find( item => inputString.Contains(item)) );

Answer 2

blackList.ForEach(new Action<string>(
    delegate(string item)
    {
        if(inputString.Contains(item)==true)
        {
            result = true;
            // I want to break here
            return;
        }
    }
));

Answer 3

The only way to "exit" the loop is to throw an exception. There is no "break" style way of exiting the .ForEach method like you would a normal foreach loop.

Answer 4

    class Program
{
    static void Main(string[] args)
    {
        List<string> blackList = new List<string>(new[] { "jaime", "jhon", "febres", "velez" });
        string inputString = "febres";
        bool result = false;
        blackList.ForEach((item) =>
                              {
                                  Console.WriteLine("Executing");
                                  if (inputString.Contains(item))
                                  {
                                      result = true;
                                      Console.WriteLine("Founded!");
                                  }
                              },
                          () => result);
        Console.WriteLine(result);
        Console.ReadLine();
    }


}
public static class MyExtensions
{
    public static void ForEach<T>(this IEnumerable<T> enumerable, Action<T> action, Func<bool> breakOn)
    {
        foreach (var item in enumerable)
        {
            action(item);
            if (breakOn())
            {
                break;
            }
        }
    }
}

Answer 5

The ForEach method is not mean to do this. If you want to know if a collection contains an item you should use the Contains method. And if you want to perform a check on all items in a collection you should try the Any extention method.

Answer 6

Do you have LINQ available to you? Your logic seems similar to Any:

bool any = blackList.Any(s=>inputString.Contains(s));

which is the same as:

bool any = blackList.Any(inputString.Contains);

If you don't have LINQ, then this is still the same as:

bool any = blackList.Find(inputString.Contains) != null;

If you want to run additional logic, there are things you can do (with LINQ) with TakeWhile etc