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| .\" $Id: curs_scanw.3x,v 1.32 2022/02/12 20:05:11 tom Exp $ |
| .TH curs_scanw 3X "" |
| .ie \n(.g .ds `` \(lq |
| .el .ds `` `` |
| .ie \n(.g .ds '' \(rq |
| .el .ds '' '' |
| .de bP |
| .ie n .IP \(bu 4 |
| .el .IP \(bu 2 |
| .. |
| .SH NAME |
| \fBscanw\fP, |
| \fBwscanw\fP, |
| \fBmvscanw\fP, |
| \fBmvwscanw\fP, |
| \fBvwscanw\fP, \fBvw_scanw\fP \- convert formatted input from a \fBcurses\fP window |
| .SH SYNOPSIS |
| \fB#include <curses.h>\fP |
| .sp |
| \fBint scanw(const char *\fIfmt\fB, ...);\fR |
| .br |
| \fBint wscanw(WINDOW *\fIwin\fB, const char *\fIfmt\fB, ...);\fR |
| .br |
| \fBint mvscanw(int \fIy\fB, int \fIx\fB, const char *\fIfmt\fB, ...);\fR |
| .br |
| \fBint mvwscanw(WINDOW *\fIwin\fB, int \fIy\fB, int \fIx\fB, const char *\fIfmt\fB, ...);\fR |
| .sp |
| \fBint vw_scanw(WINDOW *\fIwin\fB, const char *\fIfmt\fB, va_list \fIvarglist\fB);\fR |
| .sp |
| /* obsolete */ |
| .br |
| \fBint vwscanw(WINDOW *\fIwin\fB, const char *\fIfmt\fB, va_list \fIvarglist\fB);\fR |
| .SH DESCRIPTION |
| The \fBscanw\fP, \fBwscanw\fP and \fBmvscanw\fP routines are analogous to |
| \fBscanf\fP [see \fBscanf\fP(3)]. |
| The effect of these routines is as though |
| \fBwgetstr\fP were called on the window, and the resulting line used as input |
| for \fBsscanf\fP(3). |
| Fields which do not map to a variable in the \fIfmt\fP |
| field are lost. |
| .PP |
| The \fBvwscanw\fP and \fBvw_scanw\fP routines are analogous to \fBvscanf\fP(3). |
| They perform a \fBwscanw\fP using a variable argument list. |
| The third argument is a \fBva_list\fP, |
| a pointer to a list of arguments, as defined in \fB<stdarg.h>\fP. |
| .SH RETURN VALUE |
| \fBvwscanw\fP returns \fBERR\fP on failure and an integer equal to the |
| number of fields scanned on success. |
| .PP |
| Applications may use the return value from the \fBscanw\fP, \fBwscanw\fP, |
| \fBmvscanw\fP and \fBmvwscanw\fP routines to determine the number of fields |
| which were mapped in the call. |
| .PP |
| Functions with a \*(``mv\*('' prefix first perform a cursor movement using |
| \fBwmove\fP, and return an error if the position is outside the window, |
| or if the window pointer is null. |
| .SH HISTORY |
| While \fBscanw\fP was implemented in 4BSD, |
| none of the BSD releases used it until 4.4BSD (in a game). |
| That early version of curses was before the ANSI C standard. |
| It did not use <varargs.h>, though that was available. |
| In 1991 (a couple of years after SVr4 was generally available, |
| and after the C standard was published), |
| other developers updated the library, |
| using <stdarg.h> internally in 4.4BSD curses. |
| Even with this improvement, |
| BSD curses did not use function prototypes (or even declare |
| functions) in the <curses.h> header until 1992. |
| .PP |
| SVr2 documented |
| \fBscanw\fP, |
| \fBwscanw\fP |
| tersely as \*(``scanf through \fIstdscr\fP\*('' and |
| tersely as \*(``scanf through \fIwin\fP\*('', respectively. |
| .PP |
| SVr3 added |
| \fBmvscanw\fP, and |
| \fBmvwscanw\fP, with a three-line summary saying that they were analogous |
| to \fBscanf\fP(3), |
| explaining that the string which would be output from \fBscanf\fP(3) would |
| instead be output using \fBwaddstr\fP on the given window. |
| SVr3 also added \fBvwscanw\fP, saying that the third parameter |
| is a \fBva_list\fP, defined in <varargs.h>, |
| and referring the reader to the manual pages for \fIvarargs\fP and |
| \fBvprintf\fP for detailed descriptions. |
| (Because the SVr3 documentation does not mention \fBvscanf\fP, |
| that reference to \fBvprintf\fP may not be an error). |
| .PP |
| SVr4 added no new variations of \fBscanw\fP, |
| but provided for using <varargs.h> or <stdarg.h> to define the \fBva_list\fP |
| type. |
| .PP |
| X/Open Curses added \fBvw_scanw\fP to replace \fBvwscanw\fP, |
| stating that its \fBva_list\fP definition requires <stdarg.h>. |
| .SH PORTABILITY |
| In this implementation, \fBvw_scanw\fP and \fBvwscanw\fP are equivalent, |
| to support legacy applications. |
| However, the latter (\fBvwscanw\fP) is obsolete: |
| .bP |
| The XSI Curses standard, Issue 4 described these functions, |
| noting that the function |
| \fBvwscanw\fP is marked TO BE WITHDRAWN, and is to be replaced by a function |
| \fBvw_scanw\fP using the \fB<stdarg.h>\fP interface. |
| .bP |
| The Single Unix Specification, Version 2 states that |
| \fBvw_scanw\fP is preferred to \fBvwscanw\fP since the latter requires |
| including \fB<varargs.h>\fP, which |
| cannot be used in the same file as \fB<stdarg.h>\fP. |
| This implementation uses \fB<stdarg.h>\fP for both, because that header |
| is included in \fB<curses.h\fP>. |
| .bP |
| X/Open Curses, Issue 5 (December 2007) marked \fBvwscanw\fP (along with |
| \fBvwprintw\fP and the termcap interface) as withdrawn. |
| .LP |
| Both XSI and The Single Unix Specification, Version 2 state that these |
| functions return \fBERR\fP or \fBOK\fP. |
| .bP |
| Since the underlying \fBscanf\fP(3) can return the number of items scanned, |
| and the SVr4 code was documented to use this feature, |
| this is probably an editing error which was introduced in XSI, |
| rather than being done intentionally. |
| .bP |
| This implementation returns the number of items scanned, |
| for compatibility with SVr4 curses. |
| As of 2018, NetBSD curses also returns the number of items scanned. |
| Both ncurses and NetBSD curses call \fBvsscanf\fP to scan the string, |
| which returns \fBEOF\fP on error. |
| .bP |
| Portable applications should only test if the return value is \fBERR\fP, |
| since the \fBOK\fP value (zero) is likely to be misleading. |
| .IP |
| One possible way to get useful results would be to use a "%n" conversion |
| at the end of the format string to ensure that something was processed. |
| .SH SEE ALSO |
| .na |
| \fBcurses\fP(3X), |
| \fBcurs_getstr\fP(3X), |
| \fBcurs_printw\fP(3X), |
| \fBcurs_termcap\fP(3X), |
| \fBscanf\fP(3). |