ncurses-programming-howto.html

ncurses 库 可能有用酒用 没用就算了 我觉得还可以用

        }
        refresh();                      /* Print it on to the real screen */
        getch();                        /* Wait for user input */
        endwin();                       /* End curses mode                */

        return 0;
}</span></font>
</pre></td>
</tr>
</table>
</div>
<p>This program is self-explanatory. But I used functions which
aren't explained yet. The function <var class=
"LITERAL">getch()</var> is used to get a character from user. It is
equivalent to normal <var class="LITERAL">getchar()</var> except
that we can disable the line buffering to avoid &lt;enter&gt; after
input. Look for more about <var class="LITERAL">getch()</var>and
reading keys in the <a href="#KEYS">key management section</a> .
The functions attron and attroff are used to switch some attributes
on and off respectively. In the example I used them to print the
character in bold. These functions are explained in detail
later.</p>
</div>
</div>
<div class="SECT1">
<hr>
<h2 class="SECT1"><a name="AWORDWINDOWS" id="AWORDWINDOWS">5. A
Word about Windows</a></h2>
<p>Before we plunge into the myriad ncurses functions, let me clear
few things about windows. Windows are explained in detail in
following <a href="#WINDOWS">sections</a></p>
<p>A Window is an imaginary screen defined by curses system. A
window does not mean a bordered window which you usually see on
Win9X platforms. When curses is initialized, it creates a default
window named <var class="LITERAL">stdscr</var> which represents
your 80x25 (or the size of window in which you are running) screen.
If you are doing simple tasks like printing few strings, reading
input etc., you can safely use this single window for all of your
purposes. You can also create windows and call functions which
explicitly work on the specified window.</p>
<p>For example, if you call</p>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="PROGRAMLISTING">
<font color="#000000">    printw("Hi There !!!");
    refresh();</font>
</pre></td>
</tr>
</table>
<p>It prints the string on stdscr at the present cursor position.
Similarly the call to refresh(), works on stdscr only.</p>
<p>Say you have created <a href="#WINDOWS">windows</a> then you
have to call a function with a 'w' added to the usual function.</p>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="PROGRAMLISTING">
<font color="#000000">    wprintw(win, "Hi There !!!");
    wrefresh(win);</font>
</pre></td>
</tr>
</table>
<p>As you will see in the rest of the document, naming of functions
follow the same convention. For each function there usually are
three more functions.</p>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="PROGRAMLISTING">
<font color=
"#000000">    printw(string);        /* Print on stdscr at present cursor position */
    mvprintw(y, x, string);/* Move to (y, x) then print string     */
    wprintw(win, string);  /* Print on window win at present cursor position */
                           /* in the window */
    mvwprintw(win, y, x, string);   /* Move to (y, x) relative to window */
                                    /* co-ordinates and then print         */</font>
</pre></td>
</tr>
</table>
<p>Usually the w-less functions are macros which expand to
corresponding w-function with stdscr as the window parameter.</p>
</div>
<div class="SECT1">
<hr>
<h2 class="SECT1"><a name="PRINTW" id="PRINTW">6. Output
functions</a></h2>
<p>I guess you can't wait any more to see some action. Back to our
odyssey of curses functions. Now that curses is initialized, let's
interact with world.</p>
<p>There are three classes of functions which you can use to do
output on screen.</p>
<ol type="1">
<li>
<p>addch() class: Print single character with attributes</p>
</li>
<li>
<p>printw() class: Print formatted output similar to printf()</p>
</li>
<li>
<p>addstr() class: Print strings</p>
</li>
</ol>
<p>These functions can be used interchangeably and it's a matter of
style as to which class is used. Let's see each one in detail.</p>
<div class="SECT2">
<hr>
<h3 class="SECT2"><a name="ADDCHCLASS" id="ADDCHCLASS">6.1. addch()
class of functions</a></h3>
<p>These functions put a single character into the current cursor
location and advance the position of the cursor. You can give the
character to be printed but they usually are used to print a
character with some attributes. Attributes are explained in detail
in later <a href="#ATTRIB">sections</a> of the document. If a
character is associated with an attribute(bold, reverse video
etc.), when curses prints the character, it is printed in that
attribute.</p>
<p>In order to combine a character with some attributes, you have
two options:</p>
<ul>
<li>
<p>By OR'ing a single character with the desired attribute macros.
These attribute macros could be found in the header file
<var class="LITERAL">ncurses.h</var>. For example, you want to
print a character ch(of type char) bold and underlined, you would
call addch() as below.</p>
<table border="0" bgcolor="#E0E0E0" width="90%">
<tr>
<td>
<pre class="PROGRAMLISTING">
<font color="#000000">    addch(ch | A_BOLD | A_UNDERLINE);</font>
</pre></td>
</tr>
</table>
</li>
<li>
<p>By using functions like <var class=
"LITERAL">attrset(),attron(),attroff()</var>. These functions are
explained in the <a href="#ATTRIB">Attributes</a> section. Briefly,
they manipulate the current attributes of the given window. Once
set, the character printed in the window are associated with the
attributes until it is turned off.</p>
</li>
</ul>
<p>Additionally, <var class="LITERAL">curses</var> provides some
special characters for character-based graphics. You can draw
tables, horizontal or vertical lines, etc. You can find all
avaliable characters in the header file <var class=
"LITERAL">ncurses.h</var>. Try looking for macros beginning with
<var class="LITERAL">ACS_</var> in this file.</p>
</div>
<div class="SECT2">
<hr>
<h3 class="SECT2"><a name="AEN298" id="AEN298">6.2. mvaddch(),
waddch() and mvwaddch()</a></h3>
<p><var class="LITERAL">mvaddch()</var> is used to move the cursor
to a given point, and then print. Thus, the calls:</p>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="PROGRAMLISTING">
<font color=
"#000000">    move(row,col);    /* moves the cursor to row<em>th</em> row and col<em>th</em> column */
    addch(ch);</font>
</pre></td>
</tr>
</table>
can be replaced by
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="PROGRAMLISTING">
<font color="#000000">    mvaddch(row,col,ch);</font>
</pre></td>
</tr>
</table>
<p><var class="LITERAL">waddch()</var> is similar to <var class=
"LITERAL">addch()</var>, except that it adds a character into the
given window. (Note that <var class="LITERAL">addch()</var> adds a
character into the window <var class="LITERAL">stdscr</var>.)</p>
<p>In a similar fashion <var class="LITERAL">mvwaddch()</var>
function is used to add a character into the given window at the
given coordinates.</p>
<p>Now, we are familiar with the basic output function <var class=
"LITERAL">addch()</var>. But, if we want to print a string, it
would be very annoying to print it character by character.
Fortunately, <var class="LITERAL">ncurses</var> provides
<var class="LITERAL">printf</var><em>-like</em> or <var class=
"LITERAL">puts</var><em>-like</em> functions.</p>
</div>
<div class="SECT2">
<hr>
<h3 class="SECT2"><a name="PRINTWCLASS" id="PRINTWCLASS">6.3.
printw() class of functions</a></h3>
<p>These functions are similar to <var class=
"LITERAL">printf()</var> with the added capability of printing at
any position on the screen.</p>
<div class="SECT3">
<hr>
<h4 class="SECT3"><a name="PRINTWMVPRINTW" id=
"PRINTWMVPRINTW">6.3.1. printw() and mvprintw</a></h4>
<p>These two functions work much like <var class=
"LITERAL">printf()</var>. <var class="LITERAL">mvprintw()</var> can
be used to move the cursor to a position and then print. If you
want to move the cursor first and then print using <var class=
"LITERAL">printw()</var> function, use <var class=
"LITERAL">move()</var> first and then use <var class=
"LITERAL">printw()</var> though I see no point why one should avoid
using <var class="LITERAL">mvprintw()</var>, you have the
flexibility to manipulate.</p>
</div>
<div class="SECT3">
<hr>
<h4 class="SECT3"><a name="WPRINTWMVWPRINTW" id=
"WPRINTWMVWPRINTW">6.3.2. wprintw() and mvwprintw</a></h4>
<p>These two functions are similar to above two except that they
print in the corresponding window given as argument.</p>
</div>
<div class="SECT3">
<hr>
<h4 class="SECT3"><a name="VWPRINTW" id="VWPRINTW">6.3.3.
vwprintw()</a></h4>
<p>This function is similar to <var class=
"LITERAL">vprintf()</var>. This can be used when variable number of
arguments are to be printed.</p>
</div>
<div class="SECT3">
<hr>
<h4 class="SECT3"><a name="SIMPLEPRINTWEX" id=
"SIMPLEPRINTWEX">6.3.4. A Simple printw example</a></h4>
<div class="EXAMPLE"><a name="BPREX" id="BPREX"></a>
<p><b>Example 3. A Simple printw example</b></p>
<table border="0" bgcolor="#E0E0E0" width="100%">
<tr>
<td>
<pre class="PROGRAMLISTING">
<font color="#000000"><span class=
"INLINEMEDIAOBJECT">#include &lt;ncurses.h&gt;                   /* ncurses.h includes stdio.h */  
#include &lt;string.h&gt; 
 
int main()
{
 char mesg[]="Just a string";           /* message to be appeared on the screen */
 int row,col;                           /* to store the number of rows and *
                                         * the number of colums of the screen */
 initscr();                             /* start the curses mode */
 getmaxyx(stdscr,row,col);              /* get the number of rows and columns */
 mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg);
                                        /* print the message at the center of the screen */
 mvprintw(row-2,0,"This screen has %d rows and %d columns\n",row,col);
 printw("Try resizing your window(if possible) and then run this program again");
 refresh();
 getch();
 endwin();

 return 0;
}</span></font>
</pre></td>
</tr>
</table>
</div>
<p>Above program demonstrates how easy it is to use <var class=
"LITERAL">printw</var>. You just feed the coordinates and the
message to be appeared on the screen, then it does what you
want.</p>
<p>The above program introduces us to a new function <var class=
"LITERAL">getmaxyx()</var>, a macro defined in <var class=
"LITERAL">ncurses.h</var>. It gives the number of columns and the
number of rows in a given window. <var class=
"LITERAL">getmaxyx()</var> does this by updating the variables
given to it. Since <var class="LITERAL">getmaxyx()</var> is not a
function we don't pass pointers to it, we just give two integer
variables.</p>
</div>
</div>
<div class="SECT2">
<hr>
<h3 class="SECT2"><a name="ADDSTRCLASS" id="ADDSTRCLASS">6.4.
addstr() class of functions</a></h3>
<p><var class="LITERAL">addstr()</var> is used to put a character
string into a given window. This function is similar to calling
<var class="LITERAL">addch()</var> once for each character in a
given string. This is true for all output functions. There are
other functions from this family such as <var class=
"LITERAL">mvaddstr(),mvwaddstr()</var> and <var class=
"LITERAL">waddstr()</var>, which obey the naming convention of
curses.(e.g. mvaddstr() is similar to the respective calls move()
and then addstr().) Another function of this family is addnstr(),
which takes an integer parameter(say n) additionally. This function
puts at most n characters into the screen. If n is negative, then
the entire string will be added.</p>
</div>
<div class="SECT2">
<hr>
<h3 class="SECT2"><a name="ACAUTION" id="ACAUTION">6.5. A word of
caution</a></h3>
<p>All these functions take y co-ordinate first and then x in their
arguments. A common mistake by beginners is to pass x,y in that
order. If you are doing too many manipulations of (y,x)
co-ordinates, think of dividing the screen into windows and
manipulate each one separately. Windows are explained in the
<a href="#WINDOWS">windows</a> section.</p>
</div>
</div>
<div class="SECT1">
<hr>
<h2 class="SECT1"><a name="SCANW" id="SCANW">7. Input
functions</a></h2>
<p>Well, printing without taking input, is boring. Let's see
functions which allow us to get input from user. These functions
also can be divided into three categories.</p>
<ol type="1">
<li>
<p>getch() class: Get a character</p>
</li>
<li>
<p>scanw() class: Get formatted input</p>
</li>
<li>
<p>getstr() class: Get strings</p>
</li>
</ol>
<div class="SECT2">
<hr>
<h3 class="SECT2"><a name="GETCHCLASS" id="GETCHCLASS">7.1. getch()
class of functions</a></h3>
<p>These functions read a single character from the terminal. But
there are several subtle facts to consider. For example if you
don't use the function cbreak(), curses will not read your input
characters contiguously but will begin read them only after a new
line or an EOF is encountered. In order to avoid this, the cbreak()
function must used so that characters are immediately available to
your program. Another widely used function is noecho(). As the name
suggests, when this function is set (used), the characters that are
keyed in by the user will not show up on the screen. The two
functions cbreak() and noecho() are typical examples of key
management. Functions of this genre are explained in the <a href=
"#KEYS">key management section</a> .</p>