Thread: K&R symbolic constants, beginner example

Hey all..

I've been toying with this code for the past several days. I am working through all the exercises (or with a goal of completing) K&R ANSI C. Upon compiling this code and running, after typing in "apple red orange" I would like each character count for each word printed out on a new line. Currently the program is broken, and i've had it working where the first two words were outputting the correct char count, but not the digits weren't properly outputting.

Code:

/* Execise 1-13 */

#include <stdio.h>

#define	IN	1
#define OUT	0

int main(void)
{
	int c, state;
	long nc = 0;
	c = 0;
	
	int y = 0;
	
	state = OUT;
	while ((c = getchar()) != EOF)
	{
		++nc;
		if (c == ' ')
		{
			if(state == IN)
			{
				printf("\n");
				state = OUT;
			}
		} 

		else if (state == OUT)
		{
			state = IN;
			printf("%ld", nc);
		}

		else
		{
			printf("%ld", nc);
			++nc;
		}
	}
}

If I understand what you are trying to do, wouldn't it be more like this:

Code:

#include <stdio.h>
#include <ctype.h>
 
int main()
{
    enum {OUT, IN};
 
    long nc = 0;
    int c = 0;
    int state = OUT;
 
    while ((c = getchar()) != EOF)
    {
        if (isspace(c))
        {
            if(state == IN)
            {
                printf("%ld\n", nc);
                state = OUT;
                nc = 0;
            }
        } 
        else
        {
            state = IN;
            ++nc;
        }
    }
}

Or even more simply:

Code:

#include <stdio.h>
#include <ctype.h>
 
int main()
{
    long nc = 0;
    int c = 0;
 
    while ((c = getchar()) != EOF)
    {
        if (isspace(c))
        {
            if (nc > 0)
            {
                printf("%ld\n", nc);
                nc = 0;
            }
        } 
        else
            ++nc;
    }
}

The K&R program run correct, almost . . . no termination condition. The gentlemen K&R don't like this.


Your code: For what "y"? In line 12: int c = 0; And "return(0);" is missing.

Code:

//Zeilen, Wörter und Zeichen zählen, K&R S. 20 (34)


#include <stdio.h>


#define IN 1
#define OUT 0


int main(void)
{
    int c, state;
    int new_line, new_word, char_number;
    
    state = OUT;
    new_line = new_word = char_number = 0;
    do 
    {
        c = getchar();
        ++char_number;
        if (c == '\n')
            { ++new_line; }
        if (c == ' ' || c == '\n' || c == '\t')
            { state = OUT; }
        else if (state == OUT)
        {
            state = IN;
            ++new_word;
        }
    }while (c != '0');
    printf("\n%3d %3d %3d\n\n", new_line, new_word - 1, char_number);
    
    return(0);
}

"new_word - 1" because otherwise the program count also the "0".

Small correction:

Code:

do 
    {
        c = getchar();
        char_number++;
        if (c == '\n')
            { new_line++; }
        if (c == ' ' || c == '\n' || c == '\t')
            { state = OUT; }
        else if (state == OUT)
        {
            state = IN;
            new_word++;
        }
    }while (c != '0');
    //"new_word - 1" sonst wird die "0" mitgezählt
    //And so only the characters are counted without "\n".
    printf("\n%3d %3d %3d\n\n", new_line, new_word - 1, (char_number - (new_line + 1)));

Originally Posted by Kernelpanic

The K&R program run correct, almost . . . no termination condition. The gentlemen K&R don't like this.

I'm not sure what you're on about. The termination condition is end-of-file. That is, when end-of-file is reached, the program terminates.

Original code:

Code:

#include <stdio.h>


#define IN 1
#define OUT 0


int main(void)
{
    int c, state;
    int new_line, new_word, char_number;
    
    state = OUT;
    new_line = new_word = char_number = 0;
    while ((c = getchar()) != EOF) 
    {        
        char_number++;
        if (c == '\n')
            { new_line++; }
        if (c == ' ' || c == '\n' || c == '\t')
            { state = OUT; }
        else if (state == OUT)
        {
            state = IN;
            new_word++;
        }
    }    
    printf("\n%3d %3d %3d\n\n", new_line, new_word - 1, (char_number - (new_line + 1)));
    
    return(0);
}

Where is the end-of-file? Termination with "String-C" only.

Kernelpanic: In the Windows world, you can type end-of-file in a terminal with Ctrl-Z (and maybe press Enter too). In the Unix world (Linux, OS X, Cygwin, and others), type Ctrl-D instead.

What do you mean by "String-C"? Do you mean "Ctrl-C"? That forcefully terminates the program.

That's the same file in the Linux-World (Console Linux openSuSE 15 Leap):

How about this:



I typed Ctrl-D after typing the "tree" line, and it works as designed (I don't know if the results are correct, just that the program exits cleanly). Go ahead and give it a try. Type Ctrl-Z and then Enter on Windows or Ctrl-D everywhere else. That tells the program "end of file" when the input is taken from a terminal.

@Christop - No, No, No, the program from K&R is not correct.

A program has to terminated with a simple commando. Not with "String-D" or "String-C" or what ever. That's no correct!

And this original program from the Gurus is without a correct termination. That's a fact!

Originally Posted by Kernelpanic

A program has to terminated with a simple commando. Not with "String-D" or "String-C" or what ever. That's no correct!

"End of file" is about the simplest "command" there is. Besides, who says a program "has to" terminate with a simple command? Tell that to the authors of vi and emacs! (To quit vi without saving changes to a file you have to type ":q!" plus Enter.)

Keep in mind that Dennis Ritchie (the "R" in K&R) is a co-author of both the C language and Unix. He's not just some "guru". You would have to make a very strong case for why a program written by one of the creators of the language itself is "not correct".

Originally Posted by christop

Keep in mind that Dennis Ritchie (the "R" in K&R) is a co-author of both the C language and Unix. He's not just some "guru". You would have to make a very strong case for why a program written by one of the creators of the language itself is "not correct".

No, he is a human, not a new The Lord. He is only a human and no one is without mistakes.

Just out of curiosity did you check if the book has an errata for that particular section/exercise? Also do you know that there is an "answer" book for all the exercises available.

What edition of the book are you reading, if not second edition then put in a glass case since it only covers pre-standard C.?

And no matter the version do you realize that that book is quite ancient (1988, 1978) and really doesn't cover modern C?

What is your experience level? If you're a beginner then you really should consider finding a more modern book that has good reviews. IMO, that book, because of it's age should really only be used as a "reference" to the language.

Jim