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The next example is the same, except it passes information to a function rather than a subroutine. The
subroutine includes the variable answer on the RETURN instruction. The language processor replaces the
function call with the value in answer.
Using the same variables in a program and its internal subroutine or function can sometimes create
problems. In the next example, the main part of the program and the subroutine use the same control
variable, i, for their DO loops. As a result, the DO loop runs only once in the main program because the
subroutine returns to the main program with i=6.
/******************************* REXX ********************************/
/* This program receives a calculated value from an internal */
/* subroutine and uses that value in a SAY instruction. */
/*********************************************************************/
number1 = 5
number2 = 10
CALL subroutine
SAY answer /* Produces 15 */
EXIT
subroutine:
answer = number1 + number2
RETURN
Figure 29. Example of Passing Information in a Variable Using a Subroutine
/******************************* REXX ********************************/
/* This program receives a calculated value from an internal */
/* function and uses SAY to produce that value. */
/*********************************************************************/
number1 = 5
number2 = 10
SAY add() /* Produces 15 */
SAY answer /* Also produces 15 */
EXIT
add:
answer = number1 + number2
RETURN answer
Figure 30. Example of Passing Information in a Variable Using a Function
Writing Subroutines and Functions
Chapter 6. Writing Subroutines and Functions 61