Sometimes you might want to purposely write an infinite loop; for instance, in an exec that reads records from a data set until it reaches end of file, or in an exec that interacts with a user until the user enters a particular symbol to end the loop. You can use the EXIT instruction to end an infinite loop when a condition is met, as in the following example. More about the EXIT instruction appears in EXIT Instruction.

/****************************** REXX *******************************/
/* This exec prints data sets named by a user until the user enters*/
/* a null line.                                                    */
/*******************************************************************/
   DO FOREVER
     SAY 'Enter the name of the next data set or a blank to end.'
     PULL dataset_name
     IF dataset_name = '' THEN
       EXIT
     ELSE
       DO
        "PRINTDS DA("dataset_name")"
         SAY dataset_name 'printed.'
       END
   END

This example sends data sets to the printer and then issues a message that the data set was printed. When the user enters a blank, the loop ends and so does the exec. To end the loop without ending the exec, use the LEAVE instruction, as described in the following topic.