Dear C programmers,

    I'm a newbie on C and I have just wrote a very short stack programme
in C. But the programme doesn't stop decently at scanf point. Here is my
programme:
/******************************************************/
#include <stdio.h>

void main (void)
{
 int top = -1, stack[99], tmp;
 char command;
 do {
/*INPUT PROMPT*/
  printf("\n\nPUSH (p)\nPOP  (o)\nTOP  (t)\nEXIT (x)\n\n$: ");
  scanf("%c", &command);
  switch(command) {
   case 'p':
    printf("\n\n[PUSH]\nENTER NUMBER: ");
    scanf("%d", &tmp);
    stack[++top] = tmp;
    break;
   case 'o':
    printf("\n\n[POP]\nPOPPED NUMBER: %d", stack[top--]);
    break;
   case 't':
    printf("\n\n[TOP]\nTOP POSITION: %d", top);
    printf("\nTOP NUMBER: %d", stack[top]);
    break;
   default:
    break;
  }
 } while (command != 'x');
 return;

/**********************************************************/

The output didn't stop after the input prompt at scanf at the first time
AFTER any command was finished and stop only when it was encountered
again the second time. i.e. example output:

PUSH (p)
POP  (o)
TOP  (t)
EXIT (x)

$: t

[TOP]
TOP POSITION: 0
TOP NUMBER: 12

PUSH (p)
POP  (o)
TOP  (t)
EXIT (x)

$:     (<--- this is the point where scanf doesn't stop for me)

PUSH (p)
POP  (o)
TOP  (t)
EXIT (x)

$: _ (<--- this is the cursor...)

When i tried to use: int command & scanf '%c' then i can't get into the
switch at all
When i tried to use: int command & scanf '%d' then the programme doesn't
stop at any scanf at all can continue to scroll.

Can somebody please help me to clarify my concept on C and point me the
way?
Thank you very much.

Regards
        John

<snip>

you might want to take a look at the comp.lang.c FAQ, which may be
found at:-
    http://www.eskimo.com/~scs/C-faq/top.html

Particularly interesting might be:-

FAQ 11.12 "Can I declare main as void, to shut off these annoying
``main returns no value'' messages?"

FAQ 11.15 "The book I've been using always uses void main()"

FAQ 12.4 "My program's prompts and intermediate output don't always
show up on the screen"

FAQ 12.20 "Why does everyone say not to use scanf? What should I use
instead?"

and just curious; in the title of this thread what does "DATA/MEMORY
CONCEPT" mean?

--
"Perilous to us all are the devices of an art deeper than we possess
ourselves."
                Gandalf The Grey (discussing Windows NT)

Sent via Deja.com http://www.deja.com/
Before you buy.

Warning : main() should return int.

   ^^^^^^^

Try using getchar(), instead.
You need to flush the keyboard buffer, after each call to scanf().

just use :

c = getchar() ;

if ( c != '\n' )
{
   while ( ( d = getchar() ) != '\n' ) ;
   /* flushes the input buffer */

However, remember this isn't a portable solution.

int c;

   while ( ( c = getchar() ) != '\n' ) ;

Why ?

And what about

#include <stdio.h>

void flushin(void)
{
int c;
   while ((c=getchar())!='\n' && c!= EOF)
   {
   }

The good solution is in fact to use fgets().

--
-hs- "Stove"
CLC-FAQ: http://www.eskimo.com/~scs/C-faq/top.html
ISO-C Library: http://www.dinkum.com/htm_cl
"Really?  When run on my machine, a printed copy of the C FAQ leaps
from the monitor and whacks me over the head.." -- Chris Mears CLC

Read the FAQs for more informations.

This is a good solution in the case the input buffer doesn't contain
only '\n'.

Thank you you all =)