clobber.f

program clobber

c   This program illustrates the pit-falls of not watching array indices
c
c   John Mahaffy 2/14/96
c
      implicit none
      integer ndim,nd2,i
      parameter (ndim=10, nd2=ndim+2)
      real a(ndim),b(ndim),c(ndim),adat,bdat,cdat
      data adat,bdat,cdat/1.0,2.0,3.0/
      do i=1,nd2
         a(i)=adat
         b(i)=bdat
         c(i)=cdat
      enddo
c
c   From the above DO loop you would expect all elements of a to be 1.0
c   all elements of b to be 2.0, and all elements of c to be 3.0, but
c   look at the printout and see how the inappropriate DO loop index
c   maximum clobbers the first 2 elements of b and c.
c
      print *, ' i     a     b      c  '
      write (*,2000) (i,a(i),b(i),c(i),i=1,ndim)
 2000 format (i3,3f7.3)
      stop
      end