Btukfyl

I just want to know if there is a foreach oneliner in C#, like the if oneliner (exp) ? then : else.

If you're dealing with an array then you can use the built-in static ForEach method:

Array.ForEach(yourArray, x => Console.WriteLine(x));

If you're dealing with a List<T> then you can use the built-in ForEach instance method:

yourList.ForEach(x => Console.WriteLine(x));

There's nothing built-in that'll work against any arbitrary IEnumerable<T> sequence, but it's easy enough to roll your own extension method if you feel that you need it:

yourSequence.ForEach(x => Console.WriteLine(x));



// ...



public static class EnumerableExtensions

{

    public static void ForEach<T>(this IEnumerable<T> source, Action<T> action)

    {

        if (source == null) throw new ArgumentNullException("source");

        if (action == null) throw new ArgumentNullException("action");



        foreach (T item in source)

        {

            action(item);

        }

    }

}

List.ForEach Method

foreach line-liners could be achieved with LINQ extension methods. For example:

instead of:

var result = new List<string>();

foreach (var item in someCollection)

{

    result.Add(item.Title);

}

you could:

var result = someCollection.Select(x => x.Title).ToList();

Imagine you have three variables and you want to set the same property of them all in only one go:

foreach (var item in new  {labelA, labelB, labelC})

{

    item.Property= Value;

}

It is the equivalent of doing:

foreach (var item in new List<SomeType>(){labelA, labelB, labelC})

{

    item.Property= Value;

}

Sure, you can use something like List<>.ForEach:

List<String> s = new List<string>();

s.Add("This");

s.Add("Is");

s.Add("Some");

s.Add("Data");

s.ForEach(_string => Console.WriteLine(_string));

The primary difference between if and the ?operator is that if is a statement, while ? produces an expression. I.e. you can do this:

var _ = (exp) ? then : else; // ok

but not this:

var _ = if (exp) { then; } else { else; }; // error

So if you are looking for something like a foreach expression, there is no .NET type that can naturally return except for void, but there are no values of void type, so you can equally just write:

foreach (var item in collection) process(item);

In many functional languages, a Unit type is used instead of void which is a type with only one value. You can emulate this in .NET and create your own foreach expression:

class Unit

{

    public override bool Equals(object obj)

    {

        return true;

    }



    public override int GetHashCode()

    {

        return 0;

    }

}



public static class EnumerableEx

{

    public static Unit ForEach<TSource>(

        this IEnumerable<TSource> source,

        Action<TSource> action)

    {

        foreach (var item in source)

        {

            action(item);

        }



        return new Unit();

    }

}

However there hardly exists any use-case for such expressions.