Thread: doubt about kernighan and ritchie excercise 1-12

I believe you should put your buffered input into a buffer (a large char array perhaps), and then go through it, char by char, and process it - fgets() looks quite promising for that job.

I don't know if there is any way to treat buffered input, like it's sometimes buffered, and sometimes, like it's unbuffered. How would the program know which is which?

There might be some slick way to do this, but I don't know it.

And welcome to the forum. Congrats on using code tags!

What you are trying to do is very strange, but what you say you are trying to do should not be like this.

I think this issue with getchar has to do with the terminal device or shell which executes the program. I don't believe that it can be forced to pass input to the program without a newline. For stuff like that you need to use some kind of terminal library.

But I still think you should explain what this was supposed to do, even if you could echo keystrokes this way it certainly would not look like something that
prints
its
input
one
word
per
line"

So you wouldn't want to try and do this:

Code:

tthhee   iiddeeaa   ooff    tthhee   pprrooggrraamm

if you could

Can the OP (aof_1) consider storing the characters in an array?

Originally Posted by MK27

I think this issue with getchar has to do with the terminal device or shell which executes the program. I don't believe that it can be forced to pass input to the program without a newline.

I agree.

According to my C book, for getchar(), when Enter is pressed, all the characters entered, including the newline, are sent to stdin by the operating system.

Hence

Code:

if(c == '\n')
		printf("por fin lo has logrado");

prints "por fin lo has logrado".

Also, the program works the same without "state, IN, OUT" removed:

Code:

#include <stdio.h>

main()
{
 int c;

 putchar('\n');
 putchar('\n');

 while((c = getchar()) != EOF){
	if((c == ' ' || c == '\t' || c == '\n') ){
		putchar('\n');

	}
	if(c == '\n')
		printf("por fin lo has logrado");
	else if((c != ' ') && (c != '\t') && (c != '\n') ){
		putchar(c);

	}
 }
 putchar('\n');
 putchar('\n');
}

Originally Posted by afol_1

The problem is that when I input a newline (pressing enter), the program shows the output. Why the program is interpreting the -enter- as if I was asking it to evaluate the input instead of interpreting it as a newline? How can I make the program interpret the -enter- as a newline?

To answer your question, the input on your implementation is undoubtedly buffered, which means that for you to input any info at all, you need to press ENTER. In other words, when you are using a function such as getchar, the characters are held in a buffer (controlled by your operating system) until you press enter. getchar does not receive the characters you type, until you press enter. If you want some other type of behaviour, you might be able to see something in the FAQ.

As to your program, you really were on the right track. Study the following, and note the slight changes I made, hopefully making the logic a little more clear:

Code:

#include <stdio.h>

#define IN 1
#define OUT 0

int main(void)
{                               /* main returns an int. */
    int c;
    int state = OUT;            /* Assume we start outside a word, in a space. */

    while ((c = getchar()) != EOF) {
        if (c == ' ' || c == '\t' || c == '\n') {   /* We are in a space now */
            if (state == IN) {  /* Have we just now come out of a word? */

                putchar('\n');  /* Print the whitespace as a newline */

                state = OUT;    /* Change the state and check the next character */
            }  /* Else we are still in a space, so we really don't 
                * want to do anything but check the next character */
        } else {                /* We are in a word */
            putchar(c);
            state = IN;
        }
    }
    return 0;                   /* Since main returns an int, why not return an int? */
}

Originally Posted by abraham2119

@OP: why use EOF if that is only for FILE objects and in console it will not return EOF(-1) if it finished reading input.

Console returns EOF if you hit CTRL-Z (Windows/DOS etc) or CTRL-D (Linux/Unix etc), since those control characters mean EOF on a text-file (which stdin is [unless you close stdin and re-open it in binary mode - but that's really messing about with things that you probably shouldn't amessing with]).

--
Mats