Early Termination C# with Example

You can extend the functionality of existing yield methods by passing in one or more values or elements that could 
define a terminating condition within the function by calling a yield break to stop the inner loop from executing. 
 

public static IEnumerable CountUntilAny(int start, HashSet earlyTerminationSet) 
{ 
int curr = start; 
while (true) 
{ 
if (earlyTerminationSet.Contains(curr)) 
{ 
// we've hit one of the ending values 
yield break; 
} 
yield return curr; 
if (curr == Int32.MaxValue) 
{ 
// don't overflow if we get all the way to the end; just stop 
yield break; 
} 
curr++; 
} 
} 
The above method would iterate from a given start position until one of the values within the 
earlyTerminationSet was encountered. 
// Iterate from a starting point until you encounter any elements defined as 
// terminating elements 
var terminatingElements = new HashSet{ 7, 9, 11 }; 
// This will iterate from 1 until one of the terminating elements is encountered (7) 
foreach(var x in CountUntilAny(1,terminatingElements)) 
{ 
// This will write out the results from 1 until 7 (which will trigger terminating) 
Console.WriteLine(x); 
} 
Output: 
1 
2 
3 
4 
5 
6 
Live Demo on .NET Fiddle