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Use of the 76 control key as a modifier often results in a distinct code. The 77 behavior of other keys depends on whether <EM>win</EM> is in keypad mode; see 78 subsections "Keypad Mode" and "Predefined Key Codes" in <STRONG><A HREF="curs_getch.3x.html">getch(3x)</A></STRONG>. 79 80 If no input is pending, then if the no-delay flag is set in the window 81 (see <STRONG><A HREF="nodelay.3x.html">nodelay(3x)</A></STRONG>), the function returns <STRONG>ERR</STRONG>; otherwise, <EM>curses</EM> waits 82 until the terminal has input. If <STRONG><A HREF="curs_inopts.3x.html">cbreak(3x)</A></STRONG> has been called, this 83 happens after one character is read. If <STRONG><A HREF="curs_inopts.3x.html">nocbreak(3x)</A></STRONG> has been called, 84 it occurs when the next newline is read. If <STRONG><A HREF="curs_inopts.3x.html">halfdelay(3x)</A></STRONG> has been 85 called, <EM>curses</EM> waits until a character is typed or the specified delay 86 elapses. 87 88 If <STRONG><A HREF="curs_inopts.3x.html">echo(3x)</A></STRONG> has been called, and the window is not a pad, <EM>curses</EM> writes 89 <EM>wch</EM> to the window (at the cursor position) per the following rules. 90 91 <STRONG>o</STRONG> If <EM>wch</EM> matches the terminal's erase character, the cursor moves 92 leftward one position and the new position is erased as if 93 <STRONG><A HREF="curs_move.3x.html">wmove(3x)</A></STRONG> and then <STRONG><A HREF="curs_delch.3x.html">wdelch(3x)</A></STRONG> were called. When the window's 94 keypad mode is enabled (see below), <STRONG>KEY_LEFT</STRONG> and <STRONG>KEY_BACKSPACE</STRONG> are 95 handled the same way. 96 97 <STRONG>o</STRONG> <EM>curses</EM> writes any other <EM>wch</EM> to the window, as with <STRONG><A HREF="curs_add_wch.3x.html">wecho_wchar(3x)</A></STRONG>. 98 99 <STRONG>o</STRONG> If the window has been moved or modified since the last call to 100 <STRONG><A HREF="curs_refresh.3x.html">wrefresh(3x)</A></STRONG>, <EM>curses</EM> calls <STRONG>wrefresh</STRONG>. 101 102 If <EM>wch</EM> is a carriage return and <STRONG><A HREF="curs_inopts.3x.html">nl(3x)</A></STRONG> has been called, <STRONG>wgetch</STRONG> stores 103 the the character code for newline (line feed) in <EM>wch</EM> instead. 104 105 106</PRE><H3><a name="h3-Ungetting-Characters">Ungetting Characters</a></H3><PRE> 107 <STRONG>unget_wch</STRONG> places <EM>wch</EM> into the input queue to be returned by the next 108 call to <STRONG>wget_wch</STRONG>. A single input queue serves all windows. 109 110 111</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE> 112 <STRONG>wget_wch</STRONG> returns <STRONG>OK</STRONG> when it reads a wide character and <STRONG>KEY_CODE_YES</STRONG> 113 when it reads a function key code. It returns <STRONG>ERR</STRONG> if 114 115 <STRONG>o</STRONG> the <EM>WINDOW</EM> pointer is <STRONG>NULL</STRONG>, or 116 117 <STRONG>o</STRONG> its timeout expires without any data arriving, or 118 119 <STRONG>o</STRONG> execution was interrupted by a signal, in which case <STRONG>errno</STRONG> is set 120 to <STRONG>EINTR</STRONG>. 121 122 Functions prefixed with "mv" first perform cursor movement and fail if 123 the position (<EM>y</EM>, <EM>x</EM>) is outside the window boundaries. 124 125 <STRONG>unget_wch</STRONG> returns <STRONG>OK</STRONG> on success and <STRONG>ERR</STRONG> if there is no more room in the 126 input queue. 127 128 129</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE> 130 See the "NOTES" section of <STRONG><A HREF="curs_getch.3x.html">wgetch(3x)</A></STRONG>. 131 132 All of these functions except <STRONG>wget_wch</STRONG> and <STRONG>unget_wch</STRONG> may be implemented 133 as macros. 134 135 Unlike <STRONG><A HREF="curs_getch.3x.html">wgetch(3x)</A></STRONG>, <STRONG>wget_wch</STRONG> and its variants store the value of the 136 input character in an additional <EM>wch</EM> parameter instead of the return 137 value. 138 139 Unlike <STRONG>ungetch</STRONG>, <STRONG>unget_wch</STRONG> cannot distinguish function key codes 140 <STRONG>wget_wch</STRONG> from conventional character codes. An application can 141 overcome this limitation by pushing function key codes with <STRONG>ungetch</STRONG> and 142 subsequently checking the return value of <STRONG>wget_wch</STRONG> for a match with 143 <STRONG>KEY_CODE_YES</STRONG>. 144 145 146</PRE><H2><a name="h2-EXTENSIONS">EXTENSIONS</a></H2><PRE> 147 See the "EXTENSIONS" section of <STRONG><A HREF="curs_getch.3x.html">wgetch(3x)</A></STRONG>. 148 149 150</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE> 151 Applications employing <EM>ncurses</EM> extensions should condition their use on 152 the visibility of the <STRONG>NCURSES_VERSION</STRONG> preprocessor macro. 153 154 X/Open Curses, Issue 4 describes these functions. It specifies no 155 error conditions for them. 156 157 See the "PORTABILITY" section of <STRONG><A HREF="curs_getch.3x.html">wgetch(3x)</A></STRONG> regarding the interaction 158 of <STRONG>wget_wch</STRONG> with signal handlers. 159 160 161</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE> 162 <STRONG><A HREF="curs_getch.3x.html">curs_getch(3x)</A></STRONG> describes comparable functions of the <EM>ncurses</EM> library in 163 its non-wide-character configuration. 164 165 <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_add_wch.3x.html">curs_add_wch(3x)</A></STRONG>, <STRONG><A HREF="curs_inopts.3x.html">curs_inopts(3x)</A></STRONG>, <STRONG><A HREF="curs_move.3x.html">curs_move(3x)</A></STRONG>, 166 <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG> 167 168 169 170ncurses 6.5 2024-04-20 <STRONG><A HREF="curs_get_wch.3x.html">curs_get_wch(3x)</A></STRONG> 171</PRE> 172<div class="nav"> 173<ul> 174<li><a href="#h2-NAME">NAME</a></li> 175<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li> 176<li><a href="#h2-DESCRIPTION">DESCRIPTION</a> 177<ul> 178<li><a href="#h3-Reading-Characters">Reading Characters</a></li> 179<li><a href="#h3-Ungetting-Characters">Ungetting Characters</a></li> 180</ul> 181</li> 182<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li> 183<li><a href="#h2-NOTES">NOTES</a></li> 184<li><a href="#h2-EXTENSIONS">EXTENSIONS</a></li> 185<li><a href="#h2-PORTABILITY">PORTABILITY</a></li> 186<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li> 187</ul> 188</div> 189</BODY> 190</HTML> 191