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chsort@ in 64-bit programs

 
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Moji



Joined: 30 Sep 2020
Posts: 27
PostPosted: Thu Jun 15, 2023 12:25 pm    Post subject: chsort@ in 64-bit programs Reply with quote
I noticed that chsort@ behaves differently in 32-bit and 64-bit programs, when the last argument is negative. It is ignored in 32-bit, but causes run time error in a 64-bit program.

Code:
PROGRAM CHSORT_TEST
   IMPLICIT NONE
     
   INTEGER :: arr(100),N
   CHARACTER*5 :: SORT(100)
   
   WRITE (*,*) 'Start'
   
   N = -1
   call chsort@ (sort,arr,N)
 
   WRITE (*,*) 'END'
END


Last edited by Moji on Thu Jun 15, 2023 2:05 pm; edited 1 time in total
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mecej4



Joined: 31 Oct 2006
Posts: 1886
PostPosted: Thu Jun 15, 2023 1:13 pm    Post subject: Reply with quote
Your code does not issue a correct call to the FTN95 routine CHSORT@.

1. The second argument should be a character array with N elements. Your code has a scalar character variable.

2. The third argument should be the number of array elements that are to be sorted. It makes no sense to use -1 for this count, as your code does.

When a function is called with incorrect arguments, the behaviour of the program is "undefined", so what the incorrect code does in 32-bit versus 64-bit EXEs is of little to no interest.
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Kenneth_Smith



Joined: 18 May 2012
Posts: 697
Location: Hamilton, Lanarkshire, Scotland.
PostPosted: Thu Jun 15, 2023 2:16 pm    Post subject: Reply with quote
This may help:

Code:
program test_chsort
implicit none
character(len=8):: sname(1:9) = ['Smith   ','Jones   ','Taylor  ',&
                                 'Brown   ','Williams','Wilson  ',&
                                 'Watson  ','Walker  ','Walton  ']
integer :: a(1:9)
integer :: n=9
integer :: i
  call chsort@(a,sname,n)
  do i = 1, n
    print*, i, ' ', sname(a(i))
  end do
end program test_chsort


Returns

Code:
            1 Brown
            2 Jones
            3 Smith
            4 Taylor
            5 Walker
            6 Walton
            7 Watson
            8 Williams
            9 Wilson
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Moji



Joined: 30 Sep 2020
Posts: 27
PostPosted: Thu Jun 15, 2023 2:21 pm    Post subject: Re: Reply with quote
mecej4 wrote:
Your code does not issue a correct call to the FTN95 routine CHSORT@.

1. The second argument should be a character array with N elements. Your code has a scalar character variable.

2. The third argument should be the number of array elements that are to be sorted. It makes no sense to use -1 for this count, as your code does.

When a function is called with incorrect arguments, the behaviour of the program is "undefined", so what the incorrect code does in 32-bit versus 64-bit EXEs is of little to no interest.

Thanks for the comment. The first argument has been modified. You are also right about the second point. This value is however set from other codes. I just made it simple for this sample code.

I just meant, that it would be a positive point, if even for "undefined" situations, both 32-bit and 64-bit behave similarly as it is the case for many other situations, like:
Code:
      N = -1
      DO I = 1, N
        WRITE (*,*) I
      END DO
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mecej4



Joined: 31 Oct 2006
Posts: 1886
PostPosted: Thu Jun 15, 2023 7:27 pm    Post subject: Reply with quote
Please note that the four lines of code that you showed as an example of "an undefined situation" has nothing undefined about its expected behaviour. When N = -1, the subsequent DO loop is not executed at all, so the four lines of code are equivalent to just one line:
Code:
N = -1


Execution of this single statement is not expected to show any difference for 32-bit or 64-bit compilation.
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