如何读取一个不完整的表单字段，请使用C++

我有一段代码可以使用ncurses（C++）读取表单字段，但当表单字段不是完全类型时，我无法显示值。

#include <form.h>
#include <curses.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
WINDOW *chatwin, *entrywin;
FIELD  *field[1];
FORM   *fo;
void quit(void)
{
    int i;
    unpost_form(fo);
    free_form(fo);
    free_field(field[0]);
    free_field(field[1]);
    delwin(chatwin);
    endwin();
}
int main(void)
{
    int xsize, ysize;
    int charinput, i;
    char inputstring[200];
    char ttime[10];
    initscr();
    atexit(quit);
    clear();
    noecho();
    curs_set(1);
    cbreak();
    keypad(stdscr, TRUE);
    getmaxyx(stdscr, ysize, xsize);
    start_color();
    use_default_colors();
    init_pair(1, COLOR_YELLOW, COLOR_BLUE);
    init_pair(2, COLOR_BLUE, COLOR_WHITE);
    chatwin = newwin((ysize - 8), (xsize-21), 6, 21);
    entrywin = newwin(1, (xsize-21), (ysize - 1), 21);
    field[0] = new_field(1, (xsize - 21), 0, 0, 0, 10);
    field[1] = 0;
    set_form_win(fo, entrywin);
    fo = new_form(field);
    post_form(fo); 
    field_opts_on(field[0], O_STATIC);
    set_field_fore(field[0], COLOR_PAIR(2));
    set_field_back(field[0], COLOR_PAIR(2));
    refresh();
    wrefresh(chatwin);
    wrefresh(entrywin);
    while((charinput=getch()) != KEY_END)
    {
        switch(charinput)
        {
            case 10:
                snprintf(inputstring, 200, "%s", field_buffer(field[0], 0));
                struct tm *akttime;
                time_t second;
                time(&second);
                akttime = localtime(&second);
                strftime(ttime, 10, "%H:%M:%S", akttime);
                wprintw(chatwin, "<%s> %s|n", ttime, inputstring);
                wrefresh(chatwin);
                set_field_buffer(field[0], 0, "");
                wrefresh(entrywin);
                break;
            default:
                form_driver(fo, charinput);
                wrefresh(entrywin);
        }
    } 
    return(0);
}

输出

Obs.：第二行被键入：ejheeh，但输出为空

<02:31:42> dddddddkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk
                     kkkkkkkkkkk|
<02:31:45>
                                |
<02:31:51> ddddddddddddddddddddddddddddddddddddddddddddddddddddfffffff
                     fffffffffff|