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Error: Operands of logical operator '.eq.' at (1) are INTEGER(4)/HOLLERITH

I am new in Fortran. So I need help. I'm using gfortran on SUSE to compile my code and receive the following error:

200 IF ( ID .EQ. 4HEOT ) GO TO 20
1

Error: Operands of logical operator '.eq.' at (1) are INTEGER(4)/HOLLERITH


Main file for code is attached in the below link where at 1818 line shows the error.

My file's link is: https://files.engineering.com/getfile.aspx?folder=cd6961f3-d38b-4e61-a43d-269fa18c7d11&file=sfeng.f

How to fix this one?

For simplified/minimal example, I have added here the code:

SUBROUTINE CDRD ( II )

IMPLICIT DOUBLE PRECISION (A-H,O-Z)
c ohad 15/7/08
c IMPLICIT INTEGER*8 (I-N)
IMPLICIT INTEGER*4 (I-N)

C*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=C
C THIS SUBROUTINE READS PROPULSION SYSTEM DRAG DATA. C
C C
C USE NON-ZERO "II" TO WRITE TABLE DATA. C
C*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=C

CHARACTER*80 TITLE, CDFILE
DIMENSION A(100),IREP(30),IDD(4)

COMMON /UNITS / IU5, IU6, IU7, IU8, IU9, IU16, IU17, IU18
COMMON /CYUNIT/ IU3, IU4, IU10, IU11, IU12, IU13, IU14, IU15
COMMON /CYICOM/ IENG, IPRINT, NPRINT, NPDRY, NPAB, NITMAX,
1 IVAT, LIMCD
COMMON /CDSIZE/ CDNOZ(5000)
COMMON /ICDTAB/ ICDDAT(10), NTBL
COMMON /CDLOC/ LOCCD(5)
COMMON /CDFIL / CDFILE, A10, A9REF, A10REF, XNOZ, XNREF, RCRV,
1 NAB, NABREF
C======================================================================C
IU12 = 12
IUNIT = IU12
OPEN (UNIT=IUNIT, FILE=CDFILE, STATUS='OLD', ERR=9992)
REWIND (IUNIT)
NTBL = 0
NMAX = 5000
MR = 0
IF ( NTBL .EQ. 0 ) THEN
LOC = 1
DO 10 M = 1,NMAX
10 CDNOZ(M) = 0.
ENDIF

20 READ (IU12, 5000, END=400, ERR=6666 ) IP, ITABNO, TITLE

30 IF(ITABNO .EQ. 0) THEN
NREM = NMAX-LOC
IF ( II .GT. 0 ) THEN
WRITE(IU6,5010) NTBL
WRITE(IU6,5020) (N, ICDDAT(N), LOCCD(N), N = 1,NTBL)
WRITE(IU6,5030) NMAX, NREM
ENDIF
IF( MR .GT. 0 ) WRITE(IU6,5040) (IREP(IQ), IQ = 1,MR)
RETURN
ELSE
NTBL = NTBL+1
ICDDAT(NTBL) = ITABNO
LOCCD(NTBL) = LOC
IF ( NTBL .GT. 1 ) THEN
DO 40 I = 2,NTBL
IF ( ITABNO .EQ. ICDDAT(I-1) ) GO TO 50
40 CONTINUE
GO TO 150
50 MLOC = LOCCD(I-1)
ILOC = MLOC
LOCCD(I-1) = LOC
NTBL = NTBL - 1
MR = MR + 1
IREP(MR) = ITABNO
LIBLOC = 100000
DO 60 IRK = 1,NTBL
LIBRA = LOCCD(IRK)
IF ( (LIBRA .GE. MLOC) .AND. (LIBRA .LT. LIBLOC) )
* LIBLOC = LIBRA
60 CONTINUE
LEO = LIBLOC - MLOC
IF ( LEO .NE. 0 ) THEN
IZAR = LOC - 1
DO 70 I = LIBLOC,IZAR
CDNOZ(MLOC) = CDNOZ(I)
MLOC = MLOC + 1
70 CONTINUE
DO 80 I = 1,NTBL
LLOC = LOCCD(I)
IF ( LLOC .GT. ILOC ) LOCCD(I) = LLOC - LEO
80 CONTINUE
ENDIF
DO 90 I = MLOC,LOC
90 CDNOZ(I) = 0.
LOC = MLOC
ENDIF
ENDIF

150 IF ( II .GT. 0 ) THEN
WRITE ( IU6, 5060 ) ITABNO, TITLE
IP = 1
ENDIF

ICC = 0
LZ = LOC
DO 180 ICL = 1,4
180 IDD(ICL) = 4H
190 IDL = ID
READ (IU12, 5070, END=200, ERR=6666 ) ID, N, (A(I), I = 1,N)
200 IF ( ID .EQ. 4HEOT ) GO TO 20
ICC = ICC + 1
IF ( ICC .LE. 4 ) IDD(ICC) = ID
IF ( ID .EQ. IDL ) GO TO 280
IF ( ID .NE. IDD(4) ) GO TO 210
IF ( IDL .EQ. IDD(2) ) GO TO 280
LOC = LE
L = LX
GO TO 220
210 CDNOZ(LOC) = N
L = LOC
IF ( ID .EQ. IDD(3) ) LX = L
IF ( ID .NE. IDD(2) ) GO TO 260
LY = L
LZ = LZ + 1
GO TO 260

C ... WRITE THE TABULAR DATA.
220 IF ( IP .NE. 0 ) THEN
LY = LY+1
WRITE(IU6,5080) IDD(1), CDNOZ(LZ), IDD(2), CDNOZ(LY)
JF = 0
M = N
LF = LX
240 NP = M
IF ( M .GT. 8 ) NP = 8
M = M - NP
LE = LF + NP
LF = LF + 1
WRITE(IU6,5090) IDD(3), (CDNOZ(I), I = LF,LE)
LF = LE
JE = JF + NP
JF = JF + 1
WRITE(IU6,5090) IDD(4), (A(I), I = JF,JE)
JF = JE
IF( M .GT. 0 ) GO TO 240
ENDIF

260 DO 270 I = 1,N
LOC = LOC + 1
CDNOZ(LOC) = A(I)
270 CONTINUE
LE = LOC
IF ( ID .EQ. IDD(4) ) CDNOZ(LOC+2) = 1.
LOC = L + 2*N + 6
IF ( LOC .GT. NMAX ) GO TO 300
GO TO 190
280 CDNOZ(LOC) = CDNOZ(LX)
L = LOC
DO 290 I = 1,N
LOC = LOC + 1
CDNOZ(LOC) = CDNOZ(LX+I)
290 CONTINUE
GO TO 220
300 WRITE(IU6,5100) ITABNO
ITABNO = 0
GO TO 30

400 CONTINUE
ITABNO = 0
GO TO 30

6666 CONTINUE
WRITE(IU6,6669) IU12
STOP

5000 FORMAT (I1,I4,A)
5010 FORMAT (//,33X,'TABLE DATA INPUT SUMMARY, ',I3,' TABLES',//,
1 28X,'TABLE NUMBER REFERENCE NUMBER ARRAY LOCATION')
5020 FORMAT (33X,I2,12X,I5,14X,I5)
5030 FORMAT (/,36X,'DATA STORAGE ALLOCATION ',I7,/,
1 36X,'DATA STORAGE NOT USED ',I7,/)
5040 FORMAT(10X,'THE FOLLOWING TABLES HAVE BEEN REPLACED',10(I5,','))
5060 FORMAT (//,3X,I4,A,/)
5070 FORMAT(A4,I3,3X,(T11,7F10.0))
5080 FORMAT(1X,A4,' = ',E13.5,1X,A4,' = ',E13.5)
5090 FORMAT(20X,A4,1X,8E13.5)
5100 FORMAT (' ********* TABLE OVER FLOW, TABLE ',I5,' NOT LOADED')
6669 FORMAT(/,' ERROR READING ENGINE TABULAR INPUT DATA FROM UNIT',
* I3,'.',/,' PROGRAM ABORTED IN SUBROUTINE TABRD.')

9992 CONTINUE
WRITE(IU6,9999) 'ERROR OPENING THE INPUT FILE ', CDFILE,
* ' AS UNIT ', IUNIT, '.',
* 'PROGRAM ABORTED IN SUBROUTINE CDRD.'
9999 FORMAT(//,1X,2A,/,A,I2,A,/,1X,A,/)
STOP
END


4HEOT

"EOT "

EOT

3 Answers
3

You are obtaining an error because your code uses non-standard FORTRAN 77 code that your compiler (gfortran) does not support.

As gfortran detects, you are using a Hollerith constant, 4HEOT.

4HEOT

Hollerith was the predecessor of the character type. The last Fortran standard that allowed the use of Holleriths was FORTRAN 66 (ANSI X3.9-1966). Despite not being a part of the FORTRAN 77 standard, it contained an Appendix C with recommendations to processors that wanted to provide it as an extension. The use you make of the Hollerith does not even follow those recommendations, in particular:

C3. Restrictions on Hollerith Constants

A Hollerith constant may appear only in a DATA statement and in the argument list of a CALL statement.

So what is going on?

The relevant statements of your code are

IMPLICIT INTEGER*4 (I-N)
READ (IU12, 5070, END=200, ERR=6666 ) ID, N, (A(I), I = 1,N)
200 IF ( ID .EQ. 4HEOT ) GO TO 20
5070 FORMAT(A4,I3,3X,(T11,7F10.0))


Variable ID is implicitly declared as a 4-byte integer using the non-standards conforming integer*4 syntax (see Fortran: integer*4 vs integer(4) vs integer(kind=4) for more on that).

ID

integer*4

The READ statement assigns a value to ID using the A4 edit descriptor. This is the way Appendix C of the FORTRAN 77 standard allowed to read a Hollerith variable:

READ

ID

A4

C1. Hollerith data type

Hollerith is a data type; however, a symbolic name must not be of type Hollerith.
Hollerith data, other than constants, are identified under the guise of a name of type
integer, real, or logical. They must not be identified under the guise of type character. [...]

A Hollerith datum is a string of characters. [...] The blank character is significant in a Hollerith datum. Hollerith data may have an internal representation that is different from that of other data types.

An entity of type integer, real, or logical may be defined with a Hollerith value by means of a DATA statement (C4) or READ statement (C6). [...] When an entity of type integer, real, or logical is defined with a Hollerith value, the entity and its associates become undefined for use as an integer, real, or logical datum.

C6. A Editing of Hollerith Data

The Aw edit descriptor may be used with Hollerith data when the input/output list item is of type integer, real, or logical. On input, the input list item will become defined with Hollerith data. On output, the list item must be defined with Hollerith data.

Editing is as described for Aw editing of character data except that len is the maximum number of characters that can be stored in a single numeric storage unit.

So now the integer variable ID contains Hollerith data that describes 4 characters. With one character per byte, and ID defined as a 4-bytes variable, that seems fine.

ID

ID

The IF statement compares the Hollerith variable ID with the Hollerith constant 4HEOT (probably to check if you are at an End Of Table, given the context). That does not seem to be supported even by the suggested standard extension, but, hey, in the end we have two strings made of 4 characters, so deciding whether they are equal or not should not be very difficult. It's just a pitty that gfortran has never been told how to do so (ironic mode off).

IF

ID

4HEOT

How can you fix this?

I can think of a number of possibilities (in addition to finding the person who wrote this code, who is likely to be retired, and nicely asking him to fix it). The best solution for the future is Option 1:

Rewrite the code by introducing new character variables so that all I/O with character edit descriptors (A[w]) correspond to listed character variables. Replace the problematic Hollerith constant by the character constant "EOT ".

"EOT "

Some Fortran compilers are happy reading and writing integers using character edit descriptors, and are not particularly good at remembering that those integers are Hollerith variables rather than actual integers. Use one of those compilers (e.g., gfortran): as you saw, it thought that ID was still an integer, not a Hollerith. Therefore, assume that ID stays an integer, and that the read operation just reads the 4-character variable into it.

ID

ID

In this case, you can replace the Hollerith constant with the integer it would encode to. You can do this, e.g., by defining

DATA ID_EOT/4HEOT /


Now ID_EOT has an integer value (probably ICHAR("E")+256*(ICHAR("O")+256*(ICHAR("T")+256*ICHAR(" ")))) and you can replace your problematic IF statement by

ID_EOT

ICHAR("E")+256*(ICHAR("O")+256*(ICHAR("T")+256*ICHAR(" ")))

IF

200 IF ( ID .EQ. ID_EOT ) GO TO 20


This option is not standards compliant, and therefore not portable and likely to cause problems in the future (to you or other people) similar to the one you are experiencing now. However, it would at least conform to a written recommendation on how to implement the extension, which is better than what you have now.

The following compilers (versions checked) seem to support a DATA statement with a Hollerith: Intel (17.0.4), gfortran (7.3.0), CRAY (8.5.8), PGI (18.4), NAG (6.2), and Sun (8.8). Except for the NAG compiler, all of them seem to allow to read/write an integer with a character edit descriptor. Note that testing was very limited, just to the 4HEOT constant.

4HEOT

Use a compiler that can cope with your code - I believe Intel Fortran can compile and run it.

This option is not standards compliant, and therefore not portable and likely to cause problems in the future (to you or other people) similar to the one you are experiencing now. It does not even conform to the extension recommendation in Appendix C of the FORTRAN 77 standard. It is the option that requires less work, at the cost of not improving anything and keeping the problem intact for the future - when fewer people that ever coded in FORTRAN 66 will be alive.

As the compiler error says, you are comparing an integer with a HOLLERITH, that I just discovered is a string of character used before FORTRAN77 !
You cannot compare an integer with a string.

integer

HOLLERITH

string

integer

string

If you want to transform the string in integer using read, see here.

string

integer

read

If you want to compare the strings, use write instead.

write

There are a couple of workarounds. Of course it's possible to change all Hollerith constants to CHARACTER variables, but it's a little problematic given that Hollerith arguments to subprograms don't pass an extra hidden length along with them the way CHARACTER arguments do. How a Hollerith constant behaves in expressions, in compilers that support this syntax, is in general inconsistent, poorly documented, and pretty much unsupported. In DATA statements maybe better supported, but don't count on that.

Hollerith

CHARACTER

Hollerith

CHARACTER

Hollerith

DATA

gfortran says that they support Hollerith constants as function arguments, but the classic conversion functions like INT that were the first to support BOZ literals don't work: see my example below. If you like the sound of distant maniacal laughter you could send a bug report to bugzilla about this. I had more success with TRANSFER and also with an assignment:

Hollerith

INT

BOZ

TRANSFER

program holler
use ISO_FORTRAN_ENV
integer(INT32) ID
! holler.txt should exist in the current directory
! and contain at least 4 characters
open(10,file='holler.txt',status='old')
read(10,'(A4)') ID
! write(*,'(*(g0))') 'ID == 4HEOT = ',ID == 4HEOT ! Fails
! write(*,'(*(g0))') 'ID == 4HEOT = ',ID == int(4HEOT ,KIND(ID)) ! Fails
write(*,'(*(g0))') 'ID == 4HEOT = ',ID == transfer(4HEOT ,ID) ! Success
BLOCK
integer(kind(ID)) compare
compare = 4HEOT ! Note trailing space
write(*,'(*(g0))') 'ID == 4HEOT = ',ID == compare ! Success
END BLOCK
end program holler


Hollerith

TRANSFER

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