using scanf

Hey, i have a question.
I am using scanf to read in a paragraph from the keyboard and break it up into words.
I am close to doing this but I cant figure out how to make my loop stop.
When there are no more words, I would like my loop to stop, but I dont know how to check for that.
Here is what I ahve so far, any help would be appreciated.

Code:

---

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

#define MAX_SIZE 16

int main(void)
{

/* char array to hold each word with a max word size of 15 */
 char words[MAX_SIZE];

        printf("Enter a line of text: ");

/* this loop prints each word one after the other from left to right */
        while(scanf("%s", words)!= 0) {
            printf("%s\n", words);
                /*if there are no more words,
                  end loop*/
        }
}

---

How do you check to see if there are any more words left?
Also how can I equal the value of scanf("%s", words) to 1 so the loop stops.
Thanks

Use fgets to read in the entire line, then use sscanf to read from there.

>When there are no more words, I would like my loop to stop, but I dont know how to check for that.
scanf returns the number of successful conversions. If you're reading one word at a time, the number of conversions should be 1, so this will do what you want:

Code:

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while ( scanf ( "%s", words ) == 1 )
  printf ( "%s\n", words );

---

Quote:

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scanf returns the number of successful conversions. If you're reading one word at a time, the number of conversions should be 1, so this will do what you want:

Code:

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while ( scanf ( "%s", words ) == 1 )
  printf ( "%s\n", words );

---

---

Nothing changed. The loop still doesnt end. It just waits for more input.

On Windows, press Control-Z, on Linux, press Control-D.

Quote:

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Originally Posted by tabstop

Use fgets to read in the entire line, then use sscanf to read from there.

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That is a better way, that I also recommend. Note that with fgets you also read the newline ('\n') character.

Quote:

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Note that with fgets you also read the newline ('\n') character.

---

With fgets(), you can also end up with a newline at the end of your buffer. You may not, however, if, for example, the line is longer than your buffer, or if the file doesn't end with an empty line (*shudder*) and you read this last line.

Quote:

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Originally Posted by robwhit

On Windows, press Control-Z, on Linux, press Control-D.

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I need the loop to do that.

This is a very simple task, why cant anyone give me a straight answer?

example input:

hello how are you?

example output: //correct ouput

hello
how
are
you?
//END program

Right now I have output which is incorrect:

hello
how
are
you?
_ //waitting for more input

how do I terminate the loop after Ive read the last word?

Press CTRL-Z. (Assuming you're on windows.)

That's hold down the CTRL key, press the Z key, release the Z key, and then release the CTRL key.

In other words, the user has to do it. Unless you always want to quit the program when "you?" is entered or something.

[edit] The user has to indicate when the last word is read, because the computer can't tell the difference. [/edit]

Why not just use fgets() to read a line at a time, and scan the line using sscanf() (If someone already suggested that, my bad I only read the first and last post).

Quote:

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Originally Posted by gp364481

I need the loop to do that.

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You need a loop to press keys on a keyboard?

I think what the OP is trying to say is that he wants to automate the process of breaking the loop. Now that I opted to read other posts, I am the third person to suggest using fgets(). Plus if you just do as Prelude so eligantly suggested and specifically check for a valid input, you won't loop once data is input by the user. Just redesign your loop, my friend.

There are of course options other than ending the loop with CTRL-Z/D - you could for example state that a "." on it's own line or "end", "quit", "!quit" or something else is marking the end. But the computer doesn't know when you are finished without giving some sort of indication of "I'm finished".

Obviously, the end-marker should be something that is unlikely to occur in normal sane input.

--
Mats

Example:

Code:

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printf("Enter a line of text: (Or if you are done and a Windows user, press CTRL+Z, unless of course you are on *nix or Mac. If that is the case, press CTRL+D)");

---

Pretty smooth programming eh?

Quote:

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Originally Posted by master5001

Why not just use fgets() to read a line at a time, and scan the line using sscanf() (If someone already suggested that, my bad I only read the first and last post).

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I have used fgets() to get the line :

Code:

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fgets(words, 16, stdin);

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Now you say scan the line using sscanf(), how do you do that?
Sorry, im new at this.

Quote:

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Originally Posted by master5001

Example:

Code:

---

printf("Enter a line of text: (Or if you are done and a Windows user, press CTRL+Z, unless of course you are on *nix or Mac. If that is the case, press CTRL+D)");

---

Pretty smooth programming eh?

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Yes i understand. But i have specific directions that , that cant happen. The program must end on its own. All a user must do is enter the line of text.
Thanks for your replies

My last reply was some sardonic humor for some of the more advanced folk. My apologies.

Example:

Code:

---

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

#define MAX_SIZE 16

int main(void)
{
  /* char array to hold each word with a max word size of 15 */
  char words[MAX_SIZE], line[MAX_SIZE];

  printf("Enter a line of text: ");

  while(fgets(line, MAX_SIZE, stdin))
    /* this loop prints each word one after the other from left to right */
    if(sscanf(line, "&#37;s\n", words))
      printf("%s\n", words);

  return 0;
}

---

Quote:

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Originally Posted by gp364481

I have used fgets() to get the line :

Code:

---

fgets(words, 16, stdin);

---

Now you say scan the line using sscanf(), how do you do that?
Sorry, im new at this.

---

I would suggest that you make that "line" instead of words, and make the line variable say 80-1000 long.

In simple form:

Code:

---

sscanf(words, "%s", oneword);

---

However, you would need to move forward to the next word as you walk the string, so that becomes something like this:

Code:

---


...  // in the variable section of your code:
char *pline;
char line[256];
char aword[16];
...
fgets(line, sizeof(line), stdin);
...
pline = line;
while(sscanf(pline, "%s", aword))
{
    pline += strlen(aword);
    // process aword.
};

---

The above code is far from perfect - it will fail for strings that start with spaces, or strings that have words longer than 16 characters.

--
Mats

Quote:

---

Originally Posted by master5001

My last reply was some sardonic humor for some of the more advanced folk. My apologies.

Example:

Code:

---

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

#define MAX_SIZE 16

int main(void)
{
  /* char array to hold each word with a max word size of 15 */
  char words[MAX_SIZE], line[MAX_SIZE];

  printf("Enter a line of text: ");

  while(fgets(line, MAX_SIZE, stdin))
    /* this loop prints each word one after the other from left to right */
    if(sscanf(line, "%s\n", words))
      printf("%s\n", words);

  return 0;
}

---

---

You are not moving within the string.

And if it's ALWAYS one line of text, then it should call fgets() once, not using a loop.

--
Mats

Ah yes. You should swap where my fgets() is and poll feof() instead to control the loop. And as suggested, it wouldn't hurt to make the line array larger than 16 bytes.

You could always use strtok(), too (in conjunction with fgets(), that is). Assuming you don't care about the line as a whole, just about the individual words themselves.

@master5001: note that sscanf() will, when reading a string with %s or %d or any of the normal format specifiers, automatically skip over whitespace. This means that a format string as simple as "%s" would suffice.

I am wondering if the OP doesn't just want to loop through strtok() to get each individual word.

That's kind of what I said. (Though perhaps my post wasn't visible when you wrote yours.)

strtok() might not be the best function around, but it's probably going to be easier than using sscanf() or isspace() etc to walk through the string.

http://www.cplusplus.com/reference/c...ng/strtok.html

Yeah no biggy. Great minds think alike, and I am trying to read a book whilst posting. So my time between writing and submitting is very asynchronous. So it is settled, OP, use fgets() and strtok(). And forget even looping at all, actually. There is no need within the scope of this program.

Well, you pretty much have to loop to keep calling strtok(). (Unless you only care about the first word or something.)