problem with scanf Post: 91779

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Top Forums Programming problem with scanf Post 91779 by linuxpenguin on Monday 5th of December 2005 02:16:18 PM

12-05-2005

Registered User

hi,
First, fflush on stdin is not guaranteed. Some ppl might suggest you to use getchar to flush the stdin. But again that is not a clean way, i think so.
There are other options like using the gets (or fgets which is secure ) then convert the input to whatever format you want using the sscanf (string scanf). At the moment I would suggest you to use fgets and sscanf. However in instance where you want a key board input such that you dont want to wait for the enter key, for eg, u want something to happen when a user types in 'q' ( for eg) without having to press the enter key after typing q, ( this is called as hotkey) you may want to write your own keyboard handling function, I use the one below sometimes, this is for unix system. for windows, it will be different.

I have also added the main function to this function so you can better understand how mygetch works:

Code:

/* 
Desc: The main intent of this program is the function mygetch. This function is
	written to input one character at a time. The input does not await the enter
	key response from the user.
Author: Hemant Borole
Date: 27Jan05 10:06 am
*/

#include <stdio.h>
#include <termios.h>
#include <unistd.h>

#define BUFFSIZE 64		/* Buffer size for input */
/* this function will return immediately after a key is
   pressed. You do not have to wait till the enter key is hit */

int mygetch( ) {

	/* Handles to old and new termios structures */
	struct termios oldt, newt;
	int ch;

	/* store current termios to restore back later */
	tcgetattr( STDIN_FILENO, &oldt );
	newt = oldt;

	/* set to canonical. turn off echo */
	newt.c_lflag &= ~( ICANON | ECHO );
	tcsetattr( STDIN_FILENO, TCSANOW, &newt );

	/* Read the character */
	ch = getchar();

	/* Reset terminal */
	tcsetattr( STDIN_FILENO, TCSANOW, &oldt );
	return ch;
}

/* Main body, to test the mygetch, convert the character immediately
   to upper case. Do not have to wait till user inputs, presses enter
   and then convert to upper case */

int main()	{
	char c = '\0';
	char str[BUFFSIZE];
	char inp[BUFFSIZE];
	int i = 0;

	str[0] = '\0';

	printf("Type q to quit this program or press enter. \n");
	printf("Anyway the program will self kill after %d characters of input\n",BUFFSIZE);
	while ( 1 )	{
		if ( i >= BUFFSIZE ) break;

		c = mygetch();
		if ( c == 'q' || c == '\n' ) break;

		if ( c >='a' && c <='z' )	{
			printf("%c",c-32);
			str[i] = c-32;
		}
		else	{
			printf("%c",c);
			str[i] = c;
		}
		inp[i] = c;
		i++;
	}
	printf("\nYou typed: %s\n",inp);
	printf("\nConverted output: %s\n",str);
}

Last edited by blowtorch; 12-23-2006 at 01:42 PM..

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LEARN ABOUT SUNOS

wscanw

mvscanw(3XCURSES)					  X/Open Curses Library Functions					 mvscanw(3XCURSES)

NAME

       mvscanw, mvwscanw, scanw, wscanw - convert formatted input from a window

SYNOPSIS

       cc [ flag... ] file... -I /usr/xpg4/include -L /usr/xpg4/lib 
       -R /usr/xpg4/lib -lcurses [ library... ]

       c89 [ flag... ] file... -lcurses [ library... ]

       #include <curses.h>

       int mvscanw(int y, int x, char *fmt, ...);

       int mvwscanw(WINDOW *win, int y, int x, char *fmt, ...);

       int scanw(char *fmt, ...);

       int wscanw(WINDOW *win, char *fmt, ...);

PARAMETERS

       y		       Is the y (row) coordinate of the position of the character to be read.

       x		       Is the x (column) coordinate of the position of the character to be read.

       fmt		       Is a scanf() format string.

       win		       Is a pointer to the window in which the character is to be read.

DESCRIPTION

       These  functions  are  similar to scanf(3C). Their effect is as though mvwgetstr(3XCURSES) were called to get a multi-byte character string
       from the current or specified window at the current or specified cursor position, and then sscanf() were used to interpret and convert that
       string.

RETURN VALUES

       Upon successful completion, these functions return OK. Otherwise, they return ERR.

ERRORS

       No errors are defined.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Unsafe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       getnstr(3XCURSES), libcurses(3XCURSES), printw(3XCURSES), scanf(3C), wcstombs(3C), attributes(5), standards(5)

SunOS 5.10							    5 Jun 2002							 mvscanw(3XCURSES)

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