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Technical Reference: Base Operating System and Extensions , Volume 2

getch, mvgetch, mvwgetch, or wgetch Subroutine


Gets a single-byte character from the terminal.


Curses Library (libcurses.a)


#include <curses.h>
int getch(void)
int mvgetch(int y,
int x);
int mvwgetch(WINDOW *win,
int y,
int x);
int wgetch(WINDOW *win);


The getch, wgetch, mvgetch, and mvwgetch subroutines read a single-byte character from the terminal associated with the current or specified window. The results are unspecified if the input is not a single-byte character. If the keypad subroutine is enabled, these subroutines respond to the corresponding KEY_ value defined in <curses.h>.

Processing of terminal input is subject to the general rules described in Section 3.5 on page 34.

If echoing is enabled, then the character is echoed as though it were provided as an input argument to the addch subroutine, except for the following characters:


<left-arrow> and 

the current erase character:

The input is interpreted as specified in Section 3.4.3 on page 31 and then the character at the resulting cursor position is deleted as though the delch subroutine was called, except that if the cursor was originally in the first column of the line, then the user is alerted as though the beep subroutine was called.

The user is alerted as though the beep subroutine was called. Information concerning the function keys is not returned to the caller.

Function Keys

If the current or specified window is not a pad, and it has been moved or modified since the last refresh operation, then it will be refreshed before another character is read.

The Importance of Terminal Modes

The output of the getch subroutines is, in part, determined by the mode of the terminal. The following describes the action of the getch subroutines in each type of terminal mode:

Mode Action of getch Subroutines
NODELAY Returns a value of ERR if there is no input waiting.
DELAY Halts execution until the system passes text through the program. If CBREAK mode is also set, the program stops after receiving one character. If NOCBREAK mode is set, the getch subroutine stops reading after the first new line character.
HALF-DELAY Halts execution until a character is typed or a specified time out is reached. If echo is set, the character is also echoed to the window.

Note: When using the getch subroutines do not set both the NOCBREAK mode and the ECHO mode at the same time. This can cause undesirable results depending on the state of the tty driver when each character is typed.

Getting Function Keys

If your program enables the keyboard with the keypad subroutine, and the user presses a function key, the token for that function key is returned instead of raw characters. The possible function keys are defined in the /usr/include/curses.h file. Each #define macro begins with a KEY_ prefix.

If a character is received that could be the beginning of a function key (such as an Escape character) curses sets a timer. If the remainder of the sequence is not received before the timer expires, the character is passed through. Otherwise, the function key's value is returned. For this reason, after a user presses the Esc key there is a delay before the escape is returned to the program. Programmers should not use the Esc key for a single character routine.

Within the getch subroutine, a structure of type timeval, defined in the /usr/include/sys/time.h file, indicates the maximum number of microseconds to wait for the key response to complete.

The ESCDELAY environment variable sets the length of time to wait before timing out and treating the ESC keystroke as the ESC character rather than combining it with other characters in the buffer to create a key sequence. The ESCDELAY environment variable is measured in fifths of a millisecond. If ESCDELAY is 0, the system immediately composes the ESCAPE response without waiting for more information from the buffer. The user may choose any value between 0 and 99,999, inclusive. The default setting for the ESCDELAY environment variable is 500 (one tenth of a second).

Programs that do not want the getch subroutines to set a timer can call the notimeout subroutine. If notimeout is set to TRUE, curses does not distinguish between function keys and characters when retrieving data.

The getch subroutines might not be able to return all function keys because they are not defined in the terminfo database or because the terminal does not transmit a unique code when the key is pressed. The following function keys may be returned by the getch subroutines:

KEY_MIN Minimum curses key.
KEY_BREAK Break key (unreliable).
KEY_DOWN Down Arrow key.
KEY_UP Up Arrow key.
KEY_LEFT Left Arrow key.
KEY_RIGHT Right Arrow key.
KEY_HOME Home key.
KEY_F(n) Function key Fn, where n is an integer from 0 to 64.
KEY_DL Delete line.
KEY_IL Insert line.
KEY_DC Delete character.
KEY_IC Insert character or enter insert mode.
KEY_EIC Exit insert character mode.
KEY_CLEAR Clear screen.
KEY_EOS Clear to end of screen.
KEY_EOL Clear to end of line.
KEY_SF Scroll 1 line forward.
KEY_SR Scroll 1 line backwards (reverse).
KEY_NPAGE Next page.
KEY_PPAGE Previous page.
KEY_STAB Set tab.
KEY_CTAB Clear tab.
KEY_CATAB Clear all tabs.
KEY_ENTER Enter or send (unreliable).
KEY_SRESET Soft (partial) reset (unreliable).
KEY_RESET Reset or hard reset (unreliable).
KEY_PRINT Print or copy.
KEY_LL Home down or bottom (lower left).
KEY_A1 Upper-left key of keypad.
KEY_A3 Upper-right key of keypad.
KEY_B2 Center-key of keypad.
KEY_C1 Lower-left key of keypad.
KEY_C3 Lower-right key of keypad.
KEY_BTAB Back tab key.
KEY_BEG beg(inning) key
KEY_CANCEL cancel key
KEY_CLOSE close key
KEY_COMMAND cmd (command) key
KEY_COPY copy key
KEY_CREATE create key
KEY_END end key
KEY_EXIT exit key
KEY_FIND find key
KEY_HELP help key
KEY_MARK mark key
KEY_MESSAGE message key
KEY_MOVE move key
KEY_NEXT next object key
KEY_OPEN open key
KEY_OPTIONS options key
KEY_PREVIOUS previous object key
KEY_REDO redo key
KEY_REFERENCE ref(erence) key
KEY_REFRESH refresh key
KEY_REPLACE replace key
KEY_RESTART restart key
KEY_RESUME resume key
KEY_SAVE save key
KEY_SBEG shifted beginning key
KEY_SCANCEL shifted cancel key
KEY_SCOMMAND shifted command key
KEY_SCOPY shifted copy key
KEY_SCREATE shifted create key
KEY_SDC shifted delete char key
KEY_SDL shifted delete line key
KEY_SELECT select key
KEY_SEND shifted end key
KEY_SEOL shifted clear line key
KEY_SEXIT shifted exit key
KEY_SFIND shifted find key
KEY_SHELP shifted help key
KEY_SHOME shifted home key
KEY_SIC shifted input key
KEY_SLEFT shifted left arrow key
KEY_SMESSAGE shifted message key
KEY_SMOVE shifted move key
KEY_SNEXT shifted next key
KEY_SOPTIONS shifted options key
KEY_SPREVIOUS shifted prev key
KEY_SPRINT shifted print key
KEY_SREDO shifted redo key
KEY_SREPLACE shifted replace key
KEY_SRIGHT shifted right arrow
KEY_SRSUME shifted resume key
KEY_SSAVE shifted save key
KEY_SSUSPEND shifted suspend key
KEY_SUNDO shifted undo key
KEY_SUSPEND suspend key
KEY_UNDO undo key


Column Specifies the horizontal position to move the logical cursor to before getting the character.
Line Specifies the vertical position to move the logical cursor to before getting the character.
Window Identifies the window to get the character from and echo it into.

Return Values

Upon successful completion, the getch, mvwgetch, and wgetch subroutines, CURSES, and Curses Interface return the single-byte character, KEY_ value, or ERR. When in the nodelay mode and no data is available, ERR is returned.


  1. To get a character and echo it to the stdscr, use:

  2. To get a character and echo it into stdscr at the coordinates y=20, x=30, use:

    mvgetch(20, 30);
  3. To get a character and echo it into the user-defined window my_window at coordinates y=20, x=30, use:

    WINDOW *my_window;
    mvwgetch(my_window, 20, 30);

Implementation Specifics

These subroutines are part of Base Operating System (BOS) Runtime.

Related Information

The cbreak (cbreak, nocbreak, noraw, or raw Subroutine), doupdate (doupdate, refresh, wnoutrefresh, or wrefresh Subroutines), and insch (insch, mvinsch, mvwinsch, or winsch Subroutine) subroutines, keypad (keypad Subroutine) subroutine, meta (meta Subroutine) subroutine, nodelay (nodelay Subroutine) subroutine, echo or noecho (echo or noecho Subroutine) subroutine, notimeout (notimeout, timeout, wtimeout Subroutine)subroutine, ebreak or nocbreak (cbreak, nocbreak, noraw, or raw Subroutine) subroutine.

Curses Overview for Programming in AIX 5L Version 5.1 General Programming Concepts: Writing and Debugging Programs.

Manipulating Characters with Curses in AIX 5L Version 5.1 General Programming Concepts: Writing and Debugging Programs.

List of Curses Subroutines in AIX 5L Version 5.1 General Programming Concepts: Writing and Debugging Programs.

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