How to replace for-loops with a functional statement in C#?

Question

A colleague once said that God is killing a kitten every time I write a for-loop.

When asked how to avoid for-loops, his answer was to use a functional language. However

Answer 1

There's nothing wrong with for loops but here are some of the reasons people might prefer functional/declarative approaches like LINQ where you declare what you want rather than how you get it:-

1. Functional approaches are potentially easier to parallelize either manually using PLINQ or by the compiler. As CPUs move to even more cores this may become more important.

2. Functional approaches make it easier to achieve lazy evaluation in multi-step processes because you can pass the intermediate results to the next step as a simple variable which hasn't been evaluated fully yet rather than evaluating the first step entirely and then passing a collection to the next step (or without using a separate method and a yield statement to achieve the same procedurally).

3. Functional approaches are often shorter and easier to read.

4. Functional approaches often eliminate complex conditional bodies within for loops (e.g. if statements and 'continue' statements) because you can break the for loop down into logical steps - selecting all the elements that match, doing an operation on them, ...