Lazy Evaluation C# with Example

Only when the foreach statement moves to the next item does the iterator block evaluate up to the next yield 
statement. 
Consider the following example: 
private IEnumerable Integers() 
{ 
var i = 0; 
while(true) 
{ 
Console.WriteLine("Inside iterator: " + i); 
yield return i; 
i++; 
} 
} 
private void PrintNumbers() 
{ 
var numbers = Integers().Take(3); 
Console.WriteLine("Starting iteration"); 
foreach(var number in numbers) 
{ 
Console.WriteLine("Inside foreach: " + number); 
} 
} 
This will output: 
Starting iteration 
Inside iterator: 0 
Inside foreach: 0 
Inside iterator: 1 
Inside foreach: 1 
Inside iterator: 2 
Inside foreach: 2 
View Demo 
As a consequence: 
 

"Starting iteration" is printed first even though the iterator method was called before the line printing it 
because the line Integers().Take(3); does not actually starts iteration (no call to IEnumerator.MoveNext() 
was made) 
The lines printing to console alternate between the one inside the iterator method and the one inside the 
foreach, rather than all the ones inside the iterator method evaluating first 
This program terminates due to the .Take() method, even though the iterator method has a while true 
which it never breaks out of.