Article ID: 35871
Article Last Modified on 12/1/2003
APPLIES TO
- Microsoft FORTRAN Compiler 4.0
- Microsoft FORTRAN Compiler 4.1
- Microsoft FORTRAN PowerStation 1.0 Standard Edition
- Microsoft Fortran PowerStation 1.0a for MS-DOS
- Microsoft FORTRAN PowerStation 32
- Microsoft FORTRAN PowerStation 32
This article was previously published under Q35871
SYMPTOMS
The code below will generate the following output:
1.000000
2.000000
or print 1.000000 and cause a general protection fault.
CAUSE
This behavior is not a problem with Microsoft FORTRAN. The FORTRAN 77 ANSI standard, section 15.9.2, specifies that when passing a constant as an actual argument to a subroutine, the associated dummy argument (in this case x) cannot be modified.
Microsoft FORTRAN does not generate error messages while compiling. The above code does not follow the standard; therefore, it will generate unpredictable results because FORTRAN passes by reference.
RESOLUTION
If the associated dummy argument is going to be modified, pass a variable. For example, use "call sub1(y)" with y=1.
MORE INFORMATION
The following code demonstrates this information:
write (*,*) 1.0
call sub1(1.0)
write (*,*) 1.0
end
subroutine sub1(x)
real x
x = 2.0
return
end
Additional query words: 1.00 4.00 4.10 5.00 5.10
Keywords: kblangfortran KB35871
