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initscr

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initscr

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
NOTES
PORTABILITY
SEE ALSO

NAME

initscr, newterm, endwin, isendwin, set_term, delscreen − curses screen initialization and manipulation routines

SYNOPSIS

#include <ncurses/curses.h>

WINDOW *initscr(void);
int endwin(void);
bool isendwin(void);
SCREEN *newterm(char *type, FILE *outfd, FILE *infd);
SCREEN *set_term(SCREEN *new);
void delscreen(SCREEN* sp);

DESCRIPTION

initscr is normally the first curses routine to call when initializing a program. A few special routines sometimes need to be called before it; these are slk_init, filter, ripoffline, use_env. For multiple-terminal applications, newterm may be called before initscr.

The initscr code determines the terminal type and initializes all curses data structures. initscr also causes the first call to refresh to clear the screen. If errors occur, initscr writes an appropriate error message to standard error and exits; otherwise, a pointer is returned to stdscr.

A program that outputs to more than one terminal should use the newterm routine for each terminal instead of initscr. A program that needs to inspect capabilities, so it can continue to run in a line-oriented mode if the terminal cannot support a screen-oriented program, would also use newterm. The routine newterm should be called once for each terminal. It returns a variable of type SCREEN * which should be saved as a reference to that terminal. newterm’s arguments are

	•		the type of the terminal to be used in place of $TERM,
	•		a file pointer for output to the terminal, and
	•		another file pointer for input from the terminal

If the type parameter is NULL, $TERM will be used.

The program must also call endwin for each terminal being used before exiting from curses. If newterm is called more than once for the same terminal, the first terminal referred to must be the last one for which endwin is called.

A program should always call endwin before exiting or escaping from curses mode temporarily. This routine

	•		restores tty modes,
	•		moves the cursor to the lower left-hand corner of the screen and
	•		resets the terminal into the proper non-visual mode.

Calling refresh or doupdate after a temporary escape causes the program to resume visual mode.

The isendwin routine returns TRUE if endwin has been called without any subsequent calls to wrefresh, and FALSE otherwise.

The set_term routine is used to switch between different terminals. The screen reference new becomes the new current terminal. The previous terminal is returned by the routine. This is the only routine which manipulates SCREEN pointers; all other routines affect only the current terminal.

The delscreen routine frees storage associated with the SCREEN data structure. The endwin routine does not do this, so delscreen should be called after endwin if a particular SCREEN is no longer needed.

RETURN VALUE

endwin returns the integer ERR upon failure and OK upon successful completion.

Routines that return pointers always return NULL on error.

X/Open defines no error conditions. In this implementation

	•		endwin returns an error if the terminal was not initialized.
	•		newterm returns an error if it cannot allocate the data structures for the screen, or for the top-level windows within the screen, i.e., curscr, newscr, or stdscr.
	•		set_term returns no error.

NOTES

Note that initscr and newterm may be macros.

PORTABILITY

These functions are described in the XSI Curses standard, Issue 4. It specifies that portable applications must not call initscr more than once.

Old versions of curses, e.g., BSD 4.4, may have returned a null pointer from initscr when an error is detected, rather than exiting. It is safe but redundant to check the return value of initscr in XSI Curses.

If the TERM variable is missing or empty, initscr uses the value “unknown”, which normally corresponds to a terminal entry with the generic (gn) capability. Generic entries are detected by setupterm(3X) and cannot be used for full-screen operation. Other implementations may handle a missing/empty TERM variable differently.

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