Article: Q98757
Product(s): Microsoft Fortran Compiler
Version(s): 1.0
Operating System(s):
Keyword(s):
Last Modified: 24-MAR-2000
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The information in this article applies to:
- Microsoft FORTRAN PowerStation for MS-DOS, version 1.0
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SYMPTOMS
========
An application developed in Microsoft FORTRAN PowerStation that reads or writes
an array larger than 64K in size to a binary or unformatted file may read or
write an incorrect quantity of data.
CAUSE
=====
The application specifies the name of an array without a subscript or specifies
a simple variable for the subscript. The compiler does not generate the correct
code to access the low-level functions that perform binary or unformatted I/O.
Consequently, the application reads or writes the amount of data specified by
the following formula: (size of array) modulus 64K.
RESOLUTION
==========
To work around this problem, use an explicit implied DO loop in the I/O
statement. If the array has only one dimension, the array subscript must be an
expression and not a simple variable for the compiler to generate the correct
code. If the array is a multi-dimensional array, then the normal,
multi-dimensional implied DO loop is sufficient to avoid the problem.
STATUS
======
Microsoft has confirmed this to be a problem in Microsoft PowerStation version
1.0. This problem has been resolved with FORTRAN PowerStation maintenance
release version 1.0a for MS-DOS.
FORTRAN PowerStation version 1.0 can be differentiated from the maintenance
release version 1.0a by invoking the linker. Typing "link32 | more" from
\F32\BIN directory will show version 2.8 for FORTRAN PowerStation version 1.0,
and it will show version 1.0f for the maintenance release version 1.0a.
MORE INFORMATION
================
Sample Code #1
--------------
C Compile options needed: none
C This program generates the following output
C
C Program failed, number of bytes read: 1
parameter(n = 64 * 1024 + 1) ! 64K + 1 size
character*1 arr(n), chr
integer*4 i
open(1, file = 'test.dat', form = 'binary')
arr = 'x' ! initialize entire array to 'x'
write(1) arr ! write entire array
rewind(1) ! rewind to read file
do i = 1, n
read(1, iostat = ierr) chr ! read a byte at a time
if (ierr .eq. -1) exit ! exit at end of file
end do
if (i - 1 .ne. n) then
print *, 'Program failed, number of bytes read: ', i - 1
else
print *, 'Program OK, number of bytes read: ', i - 1
end if
end
Sample Code #2
--------------
C Compile options needed: none
C This program generates the following output
C
C Program OK, number of bytes read: 65537
parameter(n = 64 * 1024 + 1) ! 64K + 1 size
character*1 arr(n), chr
integer*4 i
open(1, file = 'test.dat', form = 'binary')
arr = 'x' ! initialize entire array to 'x'
write(1) (arr(i + 0), i = 1, n) ! note the addition of zero
rewind(1) ! rewind to read file
do i = 1, n
read(1, iostat = ierr) chr ! read a byte at a time
if (ierr .eq. -1) exit ! exit at end of file
end do
if (i - 1 .ne. n) then
print *, 'Program failed, number of bytes read: ', i - 1
else
print *, 'Program OK, number of bytes read: ', i - 1
end if
end
Additional query words: 1.00 buglist1.00 fixlist1.00a
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Keywords :
Technology : kbAudDeveloper kbFortranSearch kbZNotKeyword3 kbFORTRANPower100DOS
Version : :1.0
Issue type : kbbug
Solution Type : kbfix
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