• black italics indicates comments
• red bold indicates mandatory code for a typical CGI program
• red indicates typical code for a CGI program
• green indicates local peculiarities of this program
• blue bold indicates calls to CGI library items which are not normally done in main programs but demonstrate features of the underlying routines.

I provide also direct links to uncommented (at least, HTML-uncommented, ample Fortran comments inside) source code of all routines.

C
C       this is the test Fortran CGI program referred by the demos in
C       http://sax.lambrate.inaf.it/~lucio/WWW/cgi-lib/
C

C
C       these are just local variables
C

        CHARACTER prova*8,var*16,val*16,name*8
        INTEGER   ierr

C       these constants holding HTML useful strings are not here, they are instead
C       in the include file cgi.inc, where further strings can be added ad libitum
C

*       CHARACTER RED*20,BLU*20,GRN*20,BLK*7
*       PARAMETER (RED='<font color=#ff0000>')
*       PARAMETER (BLU='<font color=#0000ff>')
*       PARAMETER (GRN='<font color=#00ff00>')
*       PARAMETER (BLK='</font>')

C       this include file is referred here just to set the CGIDEBUG flag which
C       allows some debug WRITE to appear. The include file also refers to an
C       important COMMON block used internally to store the query string etc.
C       but need not to be used in the main program unless you want to play around
C       with the CGIDEBUG flag
C


        INCLUDE   'cgi.inc'
        CGIDEBUG=.TRUE.

C       these two utilities are better called first and in this order. The first is
C       actually mandatory to route the standard output where and how it has to be.
C       You select the kind of output : text/html, text/plain or whatever.
C       The second call just outputs <title>CGI program return<title>
C


        CALL CGIHEADER('text/html')
        CALL CGITOKEN('title','CGI program return')

C       this very important call retrieves the query string in POST or GET
C       method as appropriate. It is not necessary to call it in the main. It will
C       be called automatically by the first GET_NAMED_VARIABLE or GET_NEXT_VARIABLE
C       call to load the string in common. It is called here to place DEBUG information
C       first on the screen.
C

        CALL CGIRETRIEVE

C       what follows is just an example of decoding the query string for known
C       variables called by name. This works with the provaget and provapost forms,
C       but is likely to give "variable not found" if you try it with any other form
C       (including yours).
C
C       It also demonstrates HTML output. This can be generated directly with WRITE
C       statements, or by utility routines. I have made only one, CGITOKEN, which
C       outputs a string enclosed in <any>...</any> clauses.
C

        write(*,*)'<hr>'
        CALL CGITOKEN('h1','parsing 3 vars by name in 8-char buffer')

C
C       Named variables can be called in any order, provided the name matches a
C       variable in the form. Here string PROVA will contain the returned value, and
C       since this is just 8 character long, may demonstrate a truncation error. 
C        
C       Here I demonstrate the use of a variable name with imbedded URL-encoded
C       characters (look at the debug output). The variable is called 'tar$get'.
C       An error code 2 indicates truncation.   
C       The same variable is retrieved untruncated in the example loop below.
C

        NAME='tar$get'
        CALL GET_NAMED_VARIABLE(NAME,PROVA,IERR)
        CALL CGITOKEN('h3',
     .  blu//name//blk//'is '''//red//prova//blk//'''')
        write(*,*)' error code' ,ierr

C        
C       Here I demonstrate the successful use of a plain variable name 'decs'
C

        NAME='decs'
        CALL GET_NAMED_VARIABLE(NAME,PROVA,IERR)
        CALL CGITOKEN('h3',
     .  blu//name//blk//'is '''//red//prova//blk//'''')
        write(*,*)' error code' ,ierr

C        
C       Here I try to retrieve a non-existing variable 'pippo', error code -1
C

        NAME='pippo'
        CALL GET_NAMED_VARIABLE(NAME,PROVA,IERR)
        CALL CGITOKEN('h3',
     .  blu//name//blk//'is '''//red//prova//blk//'''')
        write(*,*)' error code' ,ierr

C       what follows is a more regular example of decoding the query string for all
C       variables in the order they appear. For each it will return name and value.
C
C       Some usual demo of HTML output. 
C

        write(*,*)'<hr>'
        CALL CGITOKEN('h1','parsing all variables in order')

C
C       a loop retrieving each variable in turn until end of them
C


 111    CONTINUE
        CALL GET_NEXT_VARIABLE(val,var,IERR)
        IF(IERR.NE.-1)THEN

         CALL CGITOKEN('h3','variable '//blu//val//blk)
         write(*,*)'has value ',red,var,blk
         write(*,*)' error code' ,ierr

         GOTO 111
        ENDIF

C       ok that's all
C
 
       CALL CGITOKEN('h1',grn//'end of parsing'//blk)

        STOP
        END

C       You can have a look at individual routines
C
*       include 'cgiheader.f'
*       include 'cgitoken.f'
C
C       the next two parse the query string from var=val&var=val&...&var=val
C
*       include 'get_named_variable.f'
*       include 'get_next_variable.f'
*       include 'cgiretrieve.f'
C
C       the next two are service routines to handle URL-encoding. Strings are
C       encoded by http browsers with blanks replaced by '+' and most "funny"
C       characters replaced by hexadecimal %hh sequences. Decoding reconstructs
C       the original string, e.g. a(b) from a%28b%29 . Encoding does the reverse
C       and is necessary only to match named variables, which YOU provide in
C       unencoded form as NAME arguments to GET_NAMED_VARIABLE.
C
*       include 'urldecode.f'
*       include 'urlencode.f'