Why is getchar() not working for me?

Question

I've just started programming c and I'm working through The C Programming Language by Brian W.Kernighan and Dennis M.Richie.

One of the first examples is character counting and the following program is given, but when I enter a string no result it printed.

#include <stdio.h>

main()
{
   long nc;

   nc = 0;
   while (getchar() != EOF)
          ++nc; 
   printf("%ld\n",nc);
 }

Why isn't this working?

Please describe *exactly* what *"Isn't working"* means. Does your program compile? When you run it, what input do you give it? What do you expect to happen? — abelenky, Dec 27 '13 at 00:29

score 9 · Accepted Answer · edited Jan 04 '14 at 10:41

9

You have to finish the input. Your program will count characters until EOF is encountered. EOF, in the keyboard, can be sent by pressing Ctrl-Z then ENTER if you are in Windows, or Ctrl-D then ENTER if you are in Linux/OS X.

edited Jan 04 '14 at 10:41

vahid abdi

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answered Dec 27 '13 at 00:19

mcleod_ideafix

11,128
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1

Or try `./a.out – Guido Dec 27 '13 at 00:28

score 3 · Answer 2 · answered Dec 27 '13 at 00:25

3

as an addition to the answers that were mentioned , here's how to make your program show results when pressing Enter

 #include <stdio.h>

main()
{
   long nc;

   nc = 0;
   while (getchar() != '\n')
          ++nc; 
   printf("%ld\n",nc);
 }

answered Dec 27 '13 at 00:25

Farouq Jouti

1,657
9
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score 1 · Answer 3 · edited Jan 04 '14 at 10:40

getchar() is buffered input. Since it is buffered, The control will wait until you press Enter key from the keyboard. In your program, you are checking for EOF by doing

while (getchar() != EOF)

On windows, if you want EOF, you have to input a combination of 2 keys. i.e Ctrl+Z. If you are on LINUX, then EOF is combination of 2 keys Ctrl+D

As said earlier, control will wait at console until you press Enter, so you have to press

Ctrl+Z Enter - on windows.
Ctrl+D Enter - on LINUX.

score 0 · Answer 4 · edited Jan 04 '14 at 10:40

0

You have to send EOF to program by pressing CTRL+D (for linux) or CTRL+Z (for Windows) to end the while loop.

edited Jan 04 '14 at 10:40

vahid abdi

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answered Dec 27 '13 at 00:22

Mehrdad

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Why is getchar() not working for me?

4 Answers4