Flow-control structures: Difference between revisions

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The SIGNAL statement can be thought of as a GO TO statement, however, on issuance of a SIGNAL statement, all executing DO loops and SELECTs are terminated. Essentially, that means that there is no real way to re-enter a DO loop once a SIGNAL statement is used.

Once a SIGNAL statement is executed, control passed to the first occurance of the label specified (more than one label with the same name isn't considered an error). The label can be any combination of letters, digits, periods, and some special symbols, the most common are $, #, @, !, ?, and _ (underscore or underbar). Some versions of REXX (CMS, TSO, R4) also allow the cent sign (¢).

Once a SIGNAL statement is executed, control passed to the first occurance of the label specified (more than one label with the same name isn't considered an error). The label can be any combination of letters, digits, periods, and some special symbols, the most common are '''$''', '''#''', '''@''', '''!''', '''?''', and '''_''' (underscore or underbar). Some versions of REXX (CMS, PC/REXX, Personal REXX, TSO, R4, ROO) also allow the cent sign ('''¢'''), some of those REXXes support the British pound (currency) symbol ('''£''').

The SIGNAL statement is also used to transfer control in case of some specific conditions:

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signal on failure

signal on halt

signal on lostdigits

signal on lostdigits /*newer REXXes.*/

signal on notready

signal on novalue

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signal off failure

signal off halt

signal off lostdigits

signal off lostdigits /*newer REXXes.*/

signal off notready

signal off novalue