fortran - Zero sized arrays and array bounds checking -

-

when compiled either gnu fortran (v4.4.3) or sun studio f95 (v8.3) , no array bounds checking following program runs without error. however, when array bounds checking switched on (gfortran -fbounds-check , f95 -c, respectively) gnu compiled executable runs again without error, whereas sun studio compiled executable gives run-time error,

 ******  fortran run-time system  ****** subscript out of range. location:  line 44 column 20 of 'nosize.f90' subscript number 2 has value 1 in array 't$27'

that's error in call sub2(), uses automatic array dummy argument x. sub1() calls run fine either compiler , flags.

to knowledge program "legal", in 0 sized array may referenced non-zero sized array, , there no explicit indexing of 0 length dimension of x. there 0 sized array slicing or automatic array subtlety i'm missing here? , should expect array bounds checking behave same across different compilers, or should consider vendor-specific extension?

module subs   implicit none contains       subroutine sub1(x)     implicit none     real :: x(:,:)     print*,'------------------------------------'     print*,shape(x)     print*,size(x)   end subroutine sub1    subroutine sub2(n1,n3,x)     implicit none     integer,intent(in) :: n1, n3     real :: x(n1,n3)     print*,'------------------------------------'     print*,shape(x)     print*,size(x)   end subroutine sub2 end module subs   program nosize   use subs   implicit none       integer :: n1 = 2, n2 = 2, n3 = 0   real,allocatable :: x(:,:,:)    allocate(x(n1,n2,n3))   x(:,:,:) = -99.9    print*,'allocated? ',allocated(x)   print*,'shape =',shape(x)   print*,'size  =',size(x)   print*,'x     =',x    call sub1(x(:,1,:))   call sub2(n1,n3,x(:,1,:))  end program nosize

it doesn't give problems intel's fortran compiler -check bounds; , ibm's xlf, in experience extremely strict, didn't complain -qcheck.

but more broadly, yes, there's no standard bounds checking should or shouldn't do. can see why compilers would flag assignment zero-length array being bad/wrong/weird; strange corner-case.


Comments

Post a Comment

Popular posts from this blog

php - What is the difference between $_SERVER['PATH_INFO'] and $_SERVER['ORIG_PATH_INFO']? -

-
what’s difference between $_server['path_info'] , $_server['orig_path_info'] ? how use them? when run print_r($_server) , path_info , orig_path_info not present in array. why not? how can enable them? i have read php manual on them, still don’t understand them. the path_info variable present if invoke php script this: http://www.example.com/phpinfo.php/hello_there it's /hello_there part after .php script. if don't invoke url that, there won't $_server["path_info"] environment variable. the porig_ prefix uncommon. path_info standard cgi-environment variable, , should never prefixed. did read that? (there issues around php3/php4 if invoked php interpreter via cgi-bin/ - hardly has such setups today.) for reference: http://www.ietf.org/rfc/rfc3875
Read more

fortran - Function return type mismatch -

-
i'm attempting recode old c++ program in fortran make use of lapack (i'm aware c++ have lapack++, i'm having lot of trouble installing it, gave up). i didn't have problems compilation, when had variables declared real . when started coding section of program required lapack, found parameters passed dsyev need double precision . tried change double precision (including changing hard coded numbers double precision counterparts, i.e. 0.0 -> 0.0d0) when try compile, following error of functions , subroutines i've written: error: return type mismatch of function <function> @ (1) (real(4)/real(8)) i'm not sure coming from, in program has been changed double precision. for example, i've declared following: double precision :: alpha(3),d(3),zeta1,zeta2 double precision :: a1(3),a2(3),d1(3),d2(3) double precision :: pi pi = 3.14159265359d0 alpha = (/0.109818d0, 0.405771d0, 2.22766d0/) d = (/0.444635d0, 0.535328d0, 0.154329d0 /) 10 i=1,3 ...
Read more

queue - mq_receive: message too long -

-
i implementing communication between 2 processes using queue. problem when call function mq_receive, error: message long. i have done following: struct mq_attr attr; long size = attr.mq_msgsize; .... // initializing queue "/gateway" int rc = mq_receive(gateway, buffer, size, &prio); if print size value, size=1, while when print same size program (got same mechanism), not long integer ( -1217186280 )... how can solve error?....so while size = 1, believe it's right "message long" why 1? p.s. have tried put : int rc = mq_receive(gateway, buffer, sizeof(buffer), &prio); but no result. it seems need read docs more carefully. when call mq_receive should pass size of destination buffer. this size must greater mq_msgsize attribute of queue . in addition, seems have error in queue attributes initialisation makes proper mq_receive call impossible. here standard message queue session: fill mq_attr struct ( doc ): struct mq_a...
Read more