In C# 3.0 is there any syntax for a block of code that will run only if a foreach doesn't have any iterations?

Question

meaning something like...

foreach(blah b in blahblahs)
{
    writeOnMoon(b.name);
}
default
{
    writeOnMoon("No Blahs!");
}

default or, otherwise, or something like that, if this does not exist... do you think it should?

Answer 1

Couldn't you just check blahblahs.length first?

Answer 2

how about:

    bool run = false;
    foreach (var item in collection)
    {
        run = true;
        // Do stuff
    }
    if (!run)
    {
        // Other Stuff
    }

Answer 3

No, there is not.

Answer 4

Nope, there's no specific syntax in C# that will do what you want.

You're forced to devise your own approach (like what JDunkerley's example shows).

Answer 5

There isn't a keyword to do this.

You can do:

if (blahblahs.Any())
{
    foreach(blah b in blahblahs)
    {
        writeOnMoon(b.name);
    }
}
else
{
    writeOnMoon("No Blahs!");
}

Answer 6

This doesn't exist.

I don't think this should be in the language because it really doesn't allow you to do anything new, nor does it make any current complex tasks much simpler.

Answer 7

No, but you could write an extension method so you could write:

collection.ForEachOrDefault(b =>
{
    WriteOnMoon(b.name);
}, () =>
{
    WriteOnMoon("No Blahs!");
});

Admittedly I don't think I'd recommend it... but here's the code:

public static void ForEachOrDefault<T>(this IEnumerable<T> source,
    Action<T> forEachAction, Action defaultAction)
{
    // Nullity checking omitted for brevity
    bool gotAny = false;
    foreach (T t in source)
    {
        gotAny = true;
        forEachAction(t);
    }
    if (!gotAny)
    {
        defaultAction();
    }
}

Answer 8

IEnumerable myCollection = GetCollection();
if(myCollection.Any())
{
    foreach(var item in myCollection)
    {    
        //Do something
    }
}
else
{
   // Do something else
}

Answer 9

No. But you can try to invent a simple extension method - for simple cases it will do...

public static class EnumerableExtension
{
   public static void IfEmpty<T>(this IEnumerable<T> list, Action<IEnumerable<T>> action)
   {
       if (list.Count() == 0)
         action(list);
   }
}

foreach (var v in blabla)
{
}
blabla.IfEmpty(x => log("List is empty"));

Maybe you'll even be able to create re-usable actions then. Though it doesn't really make much sense.

Answer 10

Python has this (for ... else ...) and I really miss it in C#.

With LINQ you can do something like this:

public static IEnumerable<T> IfEmpty<T>(this IEnumerable<T> source, Action action)
{
    var enumerator = source.GetEnumerator();
    if (enumerator.MoveNext())
        do yield return enumerator.Current; while (enumerator.MoveNext());
    else
        action();
}

mylistofobjects.Each(...).IfEmpty(() => { /* empty list */ });