https://wikis.ch.cam.ac.uk/ro-walesdocs/wiki/index.php?action=history&feed=atom&title=CamCASP%2FCodeExamples%2FDirectAccess 2026-04-12T04:36:21Z Revision history for this page on the wiki MediaWiki 1.39.7 https://wikis.ch.cam.ac.uk/ro-walesdocs/wiki/index.php?title=CamCASP/CodeExamples/DirectAccess&diff=1236&oldid=prev 2019-05-13T10:30:26Z

<p>Created page with &quot;&lt;pre&gt; program directaccess !Write a direct access file and read it. !Written with the hope of tracing a bug in gfortran - if it is a bug! implicit none integer, parameter ::...&quot;</p> <p><b>New page</b></p><div>&lt;pre&gt;<br /> <br /> program directaccess<br /> !Write a direct access file and read it.<br /> !Written with the hope of tracing a bug in gfortran - if it is a bug!<br /> implicit none<br /> integer, parameter :: dp = kind(1d0)<br /> !integer, parameter :: reclen = 32760 !record length<br /> integer :: reclen<br /> integer, parameter :: maxlen = 2728 !max len of arrays x() n() in a rec<br /> integer, parameter :: lenval = maxlen + 1366<br /> character(30) :: filename=&#039;tmp_directaccess.tmp&#039;<br /> integer :: fileunit<br /> integer :: stat, numrows, i, j<br /> real(dp), dimension(100000) :: values<br /> character(80) :: accesstype, fileform<br /> logical :: iexist<br /> integer :: recordlen, next_rec, num_entries<br /> <br /> fileunit = 7<br /> <br /> print *,&#039;Number of rows &#039;<br /> read *,numrows<br /> <br /> reclen=numrows*dp + 4 + 4<br /> print *,&#039;reclen = &#039;,reclen<br /> <br /> open(fileunit,file=filename,status=&#039;unknown&#039;,access=&#039;direct&#039;,&amp;<br /> recl=reclen,form=&#039;unformatted&#039;,action=&#039;readwrite&#039;,iostat=stat)<br /> print *,trim(filename),&#039; open with stat = &#039;,stat<br /> <br /> do i = 1, numrows<br /> do j = 1, numrows<br /> values(j) = real(i+j,kind=dp)<br /> enddo<br /> write(fileunit,rec=i)i+1, maxlen, values(1:numrows)<br /> enddo<br /> <br /> close(fileunit)<br /> <br /> ! Overwrite:<br /> <br /> numrows = numrows + 1000<br /> reclen=numrows*dp + 4 + 4<br /> print *,&#039;reclen = &#039;,reclen<br /> <br /> open(fileunit,file=filename,status=&#039;unknown&#039;,access=&#039;direct&#039;,&amp;<br /> recl=reclen,form=&#039;unformatted&#039;,action=&#039;readwrite&#039;,iostat=stat)<br /> print *,trim(filename),&#039; open with stat = &#039;,stat<br /> <br /> do i = 1, numrows<br /> do j = 1, numrows<br /> values(j) = real(i+2*j,kind=dp)<br /> enddo<br /> write(fileunit,rec=i)i+1, maxlen, values(1:numrows)<br /> enddo<br /> <br /> close(fileunit)<br /> <br /> <br /> open(fileunit,file=filename,status=&#039;unknown&#039;,access=&#039;direct&#039;,&amp;<br /> recl=reclen,form=&#039;unformatted&#039;,action=&#039;read&#039;,iostat=stat)<br /> <br /> inquire(file=filename,exist=iexist,access=accesstype,form=fileform,&amp;<br /> recl=recordlen)<br /> print *,&#039;Inquire: exists= &#039;,iexist<br /> print *,&#039; : access= &#039;,trim(accesstype)<br /> print *,&#039; : form = &#039;,trim(fileform)<br /> print *,&#039; : reclen= &#039;,recordlen<br /> <br /> do i = 1, min(10,numrows)<br /> read(fileunit,rec=i,iostat=stat)next_rec,num_entries,values(1:numrows)<br /> print &#039;(1x,a,4(i6,1x))&#039;,&#039;rec and stat &#039;,i,stat,next_rec,num_entries<br /> print &#039;(a,10(f5.1,1x))&#039;,&#039; vals: &#039;,values(1:10)<br /> enddo<br /> do i = max(1,numrows-10),max(10,numrows)<br /> read(fileunit,rec=i,iostat=stat)next_rec,num_entries,values(1:numrows)<br /> print &#039;(1x,a,4(i6,1x))&#039;,&#039;rec and stat &#039;,i,stat,next_rec,num_entries<br /> print &#039;(a,10(f10.1,1x))&#039;,&#039; vals: &#039;,values(1:10)<br /> enddo<br /> <br /> <br /> close(fileunit)<br /> <br /> <br /> end program directaccess<br /> <br /> &lt;/pre&gt;<br /> --[[User:am592|alston]] 12:10, 14 May 2010 (BST)</div>

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