Relation between IEnumerable and arrays

Question

What makes .Net IEnumerable so special that compiler types like arrays can be passed as an argument in its place with it being a class library interface. Is there some sort of inheritance in the background?

What actually happens when an array can interchangeably replace a collection or IEnumerable as a parameter:

public void DoJob(IEnumerable<Job> jobs)
{
}

Like this method call:

Job job = new Job();
DoJob(new [] { job });

Answer 1

Since you came from Java, I will start by telling you that in C#, there is a unified type system, where every type derives from object, unlike in Java where there are special "primitives".

So in C#, arrays are just another type. Who says they can't implement interfaces? They can! All the compiler provides is some syntax for creating them. In actuality, arrays' type is System.Array.

This is its declaration:

public abstract class Array : ICloneable, IList, ICollection, 
    IEnumerable, IStructuralComparable, IStructuralEquatable

See IEnumerable in there?

EDIT:

For IEnumerable<T>, we can find it in the language spec:

Section 12.1.2:

A one-dimensional array T[] implements the interface System.Collections.Generic.IList (IList for short) and its base interfaces.

IList<T> implements IEnumerable<T>.