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From: jt@toerring.de (Jens Thoms Toerring)
Newsgroups: comp.lang.c++
Subject: Re: reading from a temp file
Date: 28 Jun 2011 09:55:53 GMT
Organization: Freie Universitaet Berlin
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Ian Collins <ian-news@hotmail.com> wrote:
> On 06/28/11 08:34 PM, Ruben Safir wrote:
> > any clue why this isn't retrieving the contents of the temp file
> >
> > Question Deck::create_question(WINDOW* menu_win, std::ostream&os ,std::istream&in ){
> >
> >        char default_editor[20000] = "vi ";
> >        char * editor;
> >        char tmp[4096];
> >        char path[] = "/tmp/fileXXXXXX";

> Why don't you use strings?

> >        int fd;
> >        fd = mkstemp(path);
> >        editor = getenv("EDITOR");
> >        if (editor == NULL){
> >        editor  = default_editor;
> >        }
> >
> >        strcat(editor, path);

Also note that if the 'EDITOR' environment variable should be
set you're now trying to write into memory belonging to what-
ever returned the environment string. Definitely not a good
idea - while getenv() unfortunately returns a 'char *' and
not a 'char const *' (which would make this mistake impossible)
it's not meant as allowing you to modify that string (or, worse,
write past its trailing '\0').

> >        char quest_prompt[] = "Edit Your Question";
> > .....
> >        std::string input_q, input_a;
> >        while( ( c=wgetch(quest_win) ) ){

What's 'quest_win'? There's no definition before. Did you mean
'menu_win' instead?

> >        if ( (c == 10) ){
> >           def_prog_mode();
> >           endwin();

> What are these?

I suspect something related to (n)curses.

> >           system(editor);
> >           reset_prog_mode();

> and this?

> >            __gnu_cxx::stdio_filebuf<  char>   tmpfile_buf(fd, std::ios::binary|std::ios::app);

> What's one of those?

> >            std::istream is(&tmpfile_buf);

I suspect a highly system dependent attempt to obtain an input
stream from a file descriptor...

> >            is.seekg(0, std::ios::beg);
> >            while(is){

What should set 'is' to 0? Shouldn't you check for 'is.eof()'
and/or 'is.fail()'?

> >               is.read( tmp, 4096);
> >               std::cerr<<  "What did we read"<<  tmp<<  std::endl;
> >               input_q = tmp;
> >            }
> >            tmpfile_buf.close();
> >            break;
> >        }
> >        }
> >        remove(path);
                                Regards, Jens
-- 
  \   Jens Thoms Toerring  ___      jt@toerring.de
   \__________________________      http://toerring.de