Re: reading from a temp file

From:
Michael DOUBEZ <michael.doubez@free.fr>
Newsgroups:
comp.lang.c++
Date:
Fri, 1 Jul 2011 01:20:47 -0700 (PDT)
Message-ID:
<c172014c-298e-4077-a806-57e2dab95626@m22g2000yqh.googlegroups.com>
On Jun 28, 10:37 am, Ian Collins <ian-n...@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?


because mkstemp expect a char* that is modified. A solution is to
using std::vector<char> instead.

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

       strcat(editor, path);
       char quest_prompt[] = "Edit Your Question";
.....
       std::string input_q, input_a;
       while( ( c=wgetch(quest_win) ) ){
    if ( (c == 10) ){
       def_prog_mode();
       endwin();


What are these?

       system(editor);
       reset_prog_mode();


and this?


A gnu extension for building a filebuf from a file descriptor. IMO
closing the fildescriptor returned and using a simple ifstream with
path, would be less trouble.

In particular, the openmode are not good: binary will not translate
carriage return and app is irrelevant in input mode (and input mode is
missing). Use plain std::ios::in instead.

I don't know how it works in conccurent access, stdio_sync_filebuf<>
may be required here (with minimal buffer size in parameter for good
measure).

        __gnu_cxx::stdio_filebuf< char> tmpfile_buf(fd, =

std::ios::binary|std::ios::app);

What's one of those?

        std::istream is(&tmpfile_buf);
        is.seekg(0, std::ios::beg);


seekg is not guaranteed to work

        while(is){
           is.read( tmp, 4096);
           std::cerr<< "What did we read"<< tmp<< =

std::endl;

           input_q = tmp;
        }
        tmpfile_buf.close();


Note that you can dump the content of a file with:
  std::err<<is.rdbuf();

        break;
    }
       }
       remove(path);


--
Michael

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