Getchar, scanf, loops and so on

Nerox · 08-02-2004, 04:11 PM

Hello, i have a little problem which i cannot understand before, it is input keyboard functions and loops (or anything makes them to repeat)

when you do this:

int c;
do
c = getchar();
while(1);

the getchar calling function is skipped several times, (i.e. my program does not stop, it does not wait for keyboard input), and i must do the following in order to my program waits for the keyboard input:

int c;
do{
c = getchar();
while(getchar() == '\n');
}
while(1);

But i don't understand

why must i do that??

TIA

itsme86 · 08-02-2004, 04:49 PM

The logic you're using doesn't make a lot of sense. In your first loop there's no way out. The program will just sit there in the loop forever. What are you trying to accomplish? If you want to get a line of text from stdin try this:

Code:

#include <stdio.h>
#include <string.h>

int main(void)
{
  int c;

  do
  {
    c = getchar();
    printf("%c", c);
  } while(c != '\n');

  return 0;
}

Quote:

$ ./getchar
This is a string
This is a string
$

The first "This is a string" is what I typed in. The second line shows up as soon as I hit ENTER. This is exactly the way the program is expected to work.

Nerox · 08-03-2004, 01:48 AM

Thank you, i thought the program don't wait for the keyboard input, and it skip the getchar calling few times.