A simple example of the use of the preprocessor to produce
a source deck is shown in Figure 4. According to the
value assigned to the preprocessor variable USE, the source statements
will represent either a subroutine (CITYSUB) or a function (CITYFUN).
The DSNAME used for SYSPUNCH specifies a source program library
on which the preprocessor output will be placed. Normally compilation
would continue and the preprocessor output would be compiled.
Figure 4. Using the macro preprocessor to produce a source deck
//OPT4#8 JOB
//STEP2 EXEC IBMZC,PARM.PLI='MACRO,MDECK,NOCOMPILE,NOSYNTAX'
//PLI.SYSPUNCH DD DSNAME=HPU8.NEWLIB(FUN),DISP=(NEW,CATLG),UNIT=SYSDA,
// SPACE=(TRK,(1,1,1)),DCB=(RECFM=FB,LRECL=80,BLKSIZE=400)
//PLI.SYSIN DD *
/* GIVEN ZIP CODE, FINDS CITY */
%DCL USE CHAR;
%USE = 'FUN' /* FOR SUBROUTINE, %USE = 'SUB' */ ;
%IF USE = 'FUN' %THEN %DO;
CITYFUN: PROC(ZIPIN) RETURNS(CHAR(16)) REORDER; /* FUNCTION */
%END;
%ELSE %DO;
CITYSUB: PROC(ZIPIN, CITYOUT) REORDER; /* SUBROUTINE */
DCL CITYOUT CHAR(16); /* CITY NAME */
%END;
DCL (LBOUND, HBOUND) BUILTIN;
DCL ZIPIN PIC '99999'; /* ZIP CODE */
DCL 1 ZIP_CITY(7) STATIC, /* ZIP CODE - CITY NAME TABLE */
2 ZIP PIC '99999' INIT(
95141, 95014, 95030,
95051, 95070, 95008,
0), /* WILL NOT LOOK AT LAST ONE */
2 CITY CHAR(16) INIT(
'SAN JOSE', 'CUPERTINO', 'LOS GATOS',
'SANTA CLARA', 'SARATOGA', 'CAMPBELL',
'UNKNOWN CITY'); /* WILL NOT LOOK AT LAST ONE */
DCL I FIXED BIN(31);
DO I = LBOUND(ZIP,1) TO /* SEARCH FOR ZIP IN TABLE */
HBOUND(ZIP,1)-1 /* DON'T LOOK AT LAST ELEMENT */
WHILE(ZIPIN ¬= ZIP(I));
END;
%IF USE = 'FUN' %THEN %DO;
RETURN(CITY(I)); /* RETURN CITY NAME */
%END;
%ELSE %DO;
CITYOUT=CITY(I); /* RETURN CITY NAME */
%END;
END;