4570 LET L$="FAILED"

4580 IF T$<>U$ THEN 4620
4590 LET R$="FAILED"
4600 LET L$="FAILED"

4610 LET B$="F*"

4620 GOSUB 4900

4625 GOSUB 5000

4630 RETURN

4900 REM SUBROUTINE TO PRINT COMPARANDS FOR VARIABLE: VARIABLE 4910 PRINT V$; TAB(20); "V: ";W$; TAB(43);"V";

4920 RETURN

5000 REM SUBROUTINE TO PRINT RESULTS OF COMPARE

5010 PRINT TAB(47); A$; TAB(51); B$; TAB(55); L$

5020 RETURN

9000 END

PROGRAM FILE 18: THE IF-THEN STATEMENT WITH STRING OPERANDS. ANSI STANDARD 10.2, 10.4

SECTION 18.1: THE IF-THEN STATEMENT WITH STRING OPERANDS.

THIS SECTION TESTS THE COMPARISON OF STRING VARIABLES AND
CONSTANTS WITH A VARIETY OF VALUES. BOTH RELATIONSHIPS
(= AND <>) ARE TESTED FOR EACH PAIR OF VALUES. THE 'V' OR
'C' FOLLOWING THE COMPARAND VALUE INDICATES WHETHER IT IS
A VARIABLE OR A CONSTANT.

'T' OR 'F' IS PRINTED TO SHOW THE OUTCOME OF THE
COMPARISON. FOR INCORRECT COMPARES, AN '*' IS PRINTED
NEXT TO THE ERRONEOUS RESULT. WHEN DISPLAYING COMPARAND
VALUES, THE UNDERLINE CHARACTER,
IS USED TO REPRESENT

THE SPACE CHARACTER (THUS A DISPLAYED 'ONE BLANK'
INDICATES AN INTERNAL VALUE OF 'ONE BLANK').

ALSO, THE NULL STRING (LENGTH OF ZERO) IS DENOTED BY THE
LABEL (NULL STRING)'.

CHARACTER STRINGS SHOULD TEST EQUAL IF AND ONLY IF THE STRINGS ARE EQUAL IN LENGTH AND CONTAIN IDENTICAL SEQUENCES OF CHARACTERS.

10 PRINT "PROGRAM FILE 19: THE IF-THEN STATEMENT WITH NUMERIC OPERANDS"
20 PRINT "
ANSI STANDARD 10.2, 10.4′′

30 PRINT

40 PRINT "SECTION 19.1: THE IF-THEN STATEMENT WITH NUMERIC OPERANDS." 50 PRINT

60 PRINT "THIS SECTION TESTS THE COMPARISON OF NUMERIC VARIABLES AND"

70 PRINT "CONSTANTS WITH A VARIETY OF NUMERIC VALUES. ALL RELATIONSHIPS"

80 PRINT "(=, <, >, <>, <=, >=) ARE TESTED FOR EACH PAIR OF VALUES."

85 PRINT "THE 'V' OR 'C' FOLLOWING THE COMPARAND VALUE INDICATES" 90 PRINT "WHETHER IT IS A VARIABLE OR A CONSTANT."

95 PRINT

100 PRINT "'T' OR 'F' IS PRINTED TO SHOW THE OUTCOME OF THE"
105 PRINT "COMPARISON. FOR INCORRECT COMPARES, AN '*' IS PRINTED"
110 PRINT "NEXT TO THE ERRONEOUS RESULT."

*** ***

***

630 REM COMPARISONS FINISHED

640 PRINT "-1.23456E-15 C";TAB(18);": -.011E-13 C"; 650 GOSUB 5000

660 REM TEST VARIABLE: VARIABLE

670 LET A0=-0

680 LET BO=+0

690 GOSUB 2000

700 GOSUB 4400

710 LET A0=-3E36

720 LET BO=-3.001E36

730 GOSUB 3000

740 GOSUB 4400

750 LET A0=0E22

760 LET BO=1E-38

770 GOSUB 1000

780 GOSUB 4400

900 PRINT

910 PRINT "*** TEST ";R$;"

920 PRINT

930 PRINT "

940 PRINT

950 PRINT "END PROGRAM 19"

960 STOP

END TEST."

1000 REM SUBROUTINE TO INITIALIZE FOR CASE OF <

1010 LET A$="T*"

1020 LET B$="T" 1030 LET C$="T*" 1040 LET D$="T" 1050 LET E$="T" 1060 LET F$="T*" 1070 LET G$="F" 1080 LET H$="F*" 1090 LET I$="F" 1100 LET J$="F*" 1110 LET K$="F*"

1120 LET L$="F"

1140 RETURN

4090 IF +5.4321E-22 <= A0 THEN 4110

4100 LET E$=K$

4110 IF +5.4321E-22 >= AO THEN 4130

4120 LET F$=L$

4130 REM COMPARISONS FINISHED

4140 PRINT "+5.4321E-22 C";TAB(18);": ";AO;"V"; 4150 GOSUB 5000

4160 RETURN

4200 REM SUBROUTINE TO TEST VARIABLE: CONSTANT

4210 IF BO = -98765400000 THEN 4230

4220 LET A$=G$

4230 IF BO <-98765400000 THEN 4250 4240 LET B$=H$

4250 IF BO > -98765400000 THEN 4270

4260 LET C$=I$

4270 IF BO <> -98765400000 THEN 4290 4280 LET D$=J$

4290 IF BO <= -98765400000 THEN 4310

4300 LET E$=K$

4310 IF BO >= -98765400000 THEN 4330

4320 LET F$=L$

4330 REM COMPARISONS FINISHED

4340 PRINT BO; "V";TAB(18);": -98765400000 C"; 4350 GOSUB 5000

4360 RETURN

4400 REM SUBROUTINE TO TEST VARIABLE:VARIABLE

4410 IF AO = BO THEN 4430

4420 LET A$=G$

4430 IF AO < BO THEN 4450

4440 LET B$=H$

4450 IF AO > BO THEN 4470

4460 LET C$=1$

4470 IF AO <> BO THEN 4490

4480 LET D$=J$

4490 IF AO <= BO THEN 4510

4500 LET E$=K$

4510 IF AO >= BO THEN 4530

4520 LET F$=L$

4530 REM COMPARISONS FINISHED

4540 PRINT AO;"V";TAB(18);": ";BO;"V";

4550 GOSUB 5000

4560 RETURN

5000 REM SUBROUTINE TO CHECK OUT AND PRINT RESULTS OF COMPARE 5010 LET N$="