In what ways do you make use of C# Lambda Expressions?

Question

Pour in your posts. I'll start with a couple, let us see how much we can collect.

To provide inline event handlers like

button.Click += (sender,args) =>
{
};

To find items in a collection

 var dogs= animals.Where(animal => animal.Type == "dog");

For iterating a collection, like

 animals.ForEach(animal=>Console.WriteLine(animal.Name));

Let them come!!

Answer 1

Returning an custom object:

var dude = mySource.Select(x => new {Name = x.name, Surname = x.surname});

Answer 2

Casting a collection of objects.

foreach(MyCustomObject co in objects.Select(o => o As MyCustomObject))
{
    ...
}

Answer 3

Creating an accumulator.

    static Func<int, int> Foo(int n)
    {
        return a => n += a;
    }

Note the closure usage here. it's creating an accumulator that "remembers" the value of n between calls - without a class or instance variable.

Answer 4

To express an unnamed function.

Answer 5

One line function

Func<int, int> multiply = x => x * 2;
int y = multiply(4);

Answer 6

Here's a slightly different one - you can use them (like this) to simulate the missing "infoof"/"nameof" operators in C# - i.e. so that instead of hard-coding to a property name as a string, you can use a lambda. This means that it is validated at compile time (which strings can't be).

There is obviously a performance cost to this, hence "just for fun", but interesting...

Answer 7

For aggregate operations with Linq:

public Double GetLengthOfElements(string[] wordArr) {

   double count = wordArr.Sum(word => word.Length);
   return count;
}

Sure beats using foreach

Answer 8

With method invoker to update UI from a multi threaded componenet event

void Task_Progress(object sender,TaskProgressArgs  e)
{
    BeginInvoke(new MethodInvoker(() => UpdateProgress(e)));
}