Question

The following code gives digits whose name is shorter than their value. I can’t understand how LINQ understands that index should be the array index of element. Can somebody explain me…

 string[] digits = { "zero", "one", "two", "three", "four", 
                     "five", "six", "seven", "eight", "nine" };

 var shortDigits = digits.Where((digit, index) => digit.Length < index);

Answer 1

I can’t understand how linq understands that index should be the array index of element.

It’s calling the overload which takes a predicate which is given the value and the index, always. That’s the whole purpose of that overload.

From the docs for the predicate parameter:

A function to test each source element for a condition; the second parameter of the function represents the index of the source element.