# curs_scanw

## NAME



           **scanw** , **wscanw** , **mvscanw** , **mvwscanw** , **vwscanw** , **vw_scanw** - convert
           formatted input from a **curses** window
    


## SYNOPSIS



           **#include <curses.h>**
    
           **int scanw(const char ***_fmt_**, ...);**
           **int wscanw(WINDOW ***_win_**, const char ***_fmt_**, ...);**
           **int mvscanw(int** _y_**, int** _x_**, const char ***_fmt_**, ...);**
           **int mvwscanw(WINDOW ***_win_**, int** _y_**, int** _x_**, const char ***_fmt_**, ...);**
    
           **int vw_scanw(WINDOW ***_win_**, const char ***_fmt_**, va_list** _varglist_**);**
    
           /* obsolete */
           **int vwscanw(WINDOW ***_win_**, const char ***_fmt_**, va_list** _varglist_**);**
    


## DESCRIPTION



           The **scanw** , **wscanw** and **mvscanw** routines are analogous to **scanf**[see
           scanf(3)].  The effect of these routines is as though **wgetstr** were
           called on the window, and the resulting line used as input for
           sscanf(3).  Fields which do not map to a variable in the _fmt_ field
           are lost.
    
           The **vwscanw** and **vw_scanw** routines are analogous to vscanf(3).
           They perform a **wscanw** using a variable argument list.  The third
           argument is a **va_list** , a pointer to a list of arguments, as
           defined in **< stdarg.h>**.
    


## RETURN VALUE



           **vwscanw** returns **ERR** on failure and an integer equal to the number
           of fields scanned on success.
    
           Applications may use the return value from the **scanw** , **wscanw** ,
           **mvscanw** and **mvwscanw** routines to determine the number of fields
           which were mapped in the call.
    
           Functions with a “mv” prefix first perform a cursor movement using
           **wmove** , and return an error if the position is outside the window,
           or if the window pointer is null.
    


## PORTABILITY



           In this implementation, **vw_scanw** and **vwscanw** are equivalent, to
           support legacy applications.  However, the latter (**vwscanw**) is
           obsolete:
    
           •   The XSI Curses standard, Issue 4 described these functions,
               noting that the function **vwscanw** is marked TO BE WITHDRAWN,
               and is to be replaced by a function **vw_scanw** using the
               **< stdarg.h> **interface.
    
           •   The Single Unix Specification, Version 2 states that **vw_scanw**
               is preferred to **vwscanw** since the latter requires including
               **< varargs.h>**, which cannot be used in the same file as
               **< stdarg.h>**.  This implementation uses **< stdarg.h> **for both,
               because that header is included in **< curses.h**>.
    
           •   X/Open Curses, Issue 5 (December 2007) marked **vwscanw**(along
               with **vwprintw** and the termcap interface) as withdrawn.
    
           Both XSI and The Single Unix Specification, Version 2 state that
           these functions return **ERR** or **OK**.
    
           •   Since the underlying scanf(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.
    
           •   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 **vsscanf** to scan the string, which returns
               **EOF** on error.
    
           •   Portable applications should only test if the return value is
               **ERR** , since the **OK** value (zero) is likely to be misleading.
    
               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.
    


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