questions about getchar() and EOF

Ok, I am revisiting the whole getchar() and EOF thing here.

I am still working through K&R, as time permits (I work at a totally unrelated job, so sometimes I do not get a lot of time to learn C) and I got to exercise 1-8, where they want a program that counts blanks, tabs, and newlines. So anyway, I do not have the book with the answers to K&R. I do have some answers online, however they do not help me to understand the why of the whole thing, meaning that I don't really learn why I am doing stuff. It would be like me asking you guys to write the program for me. I think my problem lies with a poor understanding of getchar() and EOF. Of course some of you will likely tell me that my problems lie with a poor understanding of C... :) Anyway, if there are any of you who can help me with understanding what is going on with the question, and why my code does not do what I want it to, I would appreciate it a lot.

Here is what I did (I will list what it does when I run it following...)

Code:

---

#include <stdio.h>

/* Program to count blanks, tabs, and newlines (Exercise 1-8 in K&R) */

int main(void)
{
  int c, nl, tab, blank;

  nl = 0;
  tab = 0;
  blank = 0;

  while ( ( c = getchar() ) != EOF )
    if ( c == '\n' )
      ++nl;
  printf( "There were %d new lines\n", nl );

  if ( c == '\t' )
    ++tab;
  printf( "There were %d tabs\n", tab );


  if ( c == ' ' )
    ++blank;
  printf( "There were %d blanks\n", blank );

  return 0;
}

---

Ok, so here is what happens when I run it:

Quote:

---

[Tue Feb 4 ~/cprograms]$count_tabs
testing my program. a tab here, and some spaces here

and then a new line

and another tab and then another, and another,

newline

There were 8 new lines
There were 0 tabs
There were 0 blanks

---

It seems to do the newlines thing right, but it better, as it is basically right out of the book. Anyway, enough out of me here, as I don't get it. Hopefully someone will help. Thanks.

kermit

Quote:

---

Code:

---

while ( ( c = getchar() ) != EOF )

    if ( c == '\n' )
      ++nl;
    printf( "There were %d new lines\n", nl );

  if ( c == '\t' )
    ++tab;
  printf( "There were %d tabs\n", tab );


  if ( c == ' ' )
    ++blank;
  printf( "There were %d blanks\n", blank );

---

---

You need to use { } so that the code is considered the same block. See below:

Code:

---

while ( ( c = getchar() ) != EOF )
{
    if ( c == '\n' )
        ++nl;
    printf( "There were %d new lines\n", nl );

    if ( c == '\t' )
        ++tab;
    printf( "There were %d tabs\n", tab );

    if ( c == ' ' )
        ++blank;
    printf( "There were %d blanks\n", blank );
}

---

That way all three if checks are used each time through the loop.

Quzah.

Ok, this helps me. It 'works' a bit better now. I still have to play with it to get it to stop (I hit enter for a new line and it blasted the output onto the terminal a number of times, but from here I can carry on and see if I can make it do what I want to. I will return if I can't get it. Thanks for the tip, Quzah.

kermit

From the keyboard, EOF is usually CTRL+D or CTRL+Z, OS dependant.

Quzah.

Can be CTRL+C too...