Purpose
When you use the yield keyword in a statement, you indicate that the method, operator, or get accessor in which it appears is an iterator.
Syntax
YIELD RETURN <expression>
YIELD (EXIT|BREAK)
Arguments
| YIELD RETURN | You use YIELD RETURN <expression> to return each element one at a time. |
| YIELD [BREAK|EXIT] | You use YIELD BREAK or YIELD EXIT to end the iteration. |
Examples
using System.Collections.Generic
// The Yield return statement allows you to create code that returns a
// collection of values without having to create the collection in memory first.
// The compiler will create code that "remembers" where you were inside the
// loop and returns to that spot.
FUNCTION Start AS VOID
FOREACH nYear AS INT IN GetAllLeapYears(1896, 2040)
? "Year", nYear, "is a leap year."
NEXT
Console.ReadLine()
RETURN
FUNCTION GetAllLeapYears(nMin AS INT, nMax AS INT) AS IEnumerable<INT>
FOR LOCAL nYear := nMin AS INT UPTO nMax
IF nYear % 4 == 0 .and. (nYear % 100 != 0 .or. nYear % 400 == 0)
YIELD RETURN nYear
END IF
IF nYear == 2012
YIELD EXIT // Exit the loop
ENDIF
NEXT
