Re: reading from a temp file

From:

Ruben Safir <mrbrklyn@panix.com>

Newsgroups:

comp.lang.c++

Date:

Sat, 2 Jul 2011 00:47:27 +0000 (UTC)

Message-ID:

<iulpqv$n0n$1@reader1.panix.com>

Michael DOUBEZ <michael.doubez@free.fr> wrote:

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 ,st=

d::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.

std::vector<char> or std::vector<char *> ?

       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.

Those above are part of ncures.h, but those below as was you describe.

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.

The editor is creating a text file so you might be correct, but I don't
think I want carriage returns altered or interpreted, just eventually
dumped into a data file at 4096 bit clips. And I don't want to deal
with deliminators or terminators on input, or output, which is a problem
with getline and getchar. I want them included in the input stream,
whole.

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).

It didn't have trouble with two seperate streams from the same fd. I
did have trouble using one stream for both in and out.

__gnu_cxx::stdio_filebuf< char> tmpfile_buf(f=

d, 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

Upon input? It didn't work away. I thought maybe I as set to the end
of the stream but it didn't like binary mode at all, and the eof bits
behaved as I expected so I can only guess that it was behaving OK.

        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();

I want a guaranteed chunk of 4096, no greater.

        break;
    }
       }
       remove(path);

--
Michael