The Single UNIX ® Specification, Version 2
Copyright © 1997 The Open Group


clearok, idlok, leaveok, scrollok, setscrreg, wsetscrreg - terminal output control functions


#include <curses.h>

int clearok(WINDOW *win, bool bf);

int idlok(WINDOW *win, bool bf);

int leaveok(WINDOW *win, bool bf);

int scrollok(WINDOW *win, bool bf);

int setscrreg(int top, int bot);

int wsetscrreg(WINDOW *win, int top, int bot);


These functions set options that deal with output within Curses.

The clearok() function assigns the value of bf to an internal flag in the specified window that governs clearing of the screen during a refresh. If, during a refresh operation on the specified window, the flag in curscr is TRUE or the flag in the specified window is TRUE, then the implementation clears the screen, redraws it in its entirety, and sets the flag to FALSE in curscr and in the specified window. The initial state is unspecified.

The idlok() function specifies whether the implementation may use the hardware insert-line, delete-line, and scroll features of terminals so equipped. If bf is TRUE, use of these features is enabled. If bf is FALSE, use of these features is disabled and lines are instead redrawn as required. The initial state is FALSE.

The leaveok() function controls the cursor position after a refresh operation. If bf is TRUE, refresh operations on the specified window may leave the terminal's cursor at an arbitrary position. If bf is FALSE, then at the end of any refresh operation, the terminal's cursor is positioned at the cursor position contained in the specified window. The initial state is FALSE.

The scrollok() function controls the use of scrolling. If bf is TRUE, then scrolling is enabled for the specified window, with the consequences discussed in Truncation, Wrapping and Scrolling . If bf is FALSE, scrolling is disabled for the specified window. The initial state is FALSE.

The setscrreg() and wsetscrreg() functions define a software scrolling region in the current or specified window. The top and bot arguments are the line numbers of the first and last line defining the scrolling region. (Line 0 is the top line of the window.) If this option and scrollok() are enabled, an attempt to move off the last line of the margin causes all lines in the scrolling region to scroll one line in the direction of the first line. Only characters in the window are scrolled. If a software scrolling region is set and scrollok() is not enabled, an attempt to move off the last line of the margin does not reposition any lines in the scrolling region.


Upon successful completion, setscrreg() and wsetscrreg() return OK. Otherwise, they return ERR.

The other functions always return OK.


No errors are defined.


The only reason to enable the idlok() feature is to use scrolling to achieve the visual effect of motion of a partial window, such as for a screen editor. In other cases, the feature can be visually annoying.

The leaveok() option provides greater efficiency for applications that do not use the cursor.


clear(), delscreen(), doupdate(), scrl(), <curses.h>.

UNIX ® is a registered Trademark of The Open Group.
Copyright © 1997 The Open Group
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