Clearing Buffer Problem (beginners Q)

Hello,

I have run into this problem before but have always been able to sneak around it, but, now I really have to figure out what I'm doing wrong.

Basically when I enter input that is to big ie...234327432 words, it stays in the buffer, so it always promps the user that their input is to big.

I thought the command;

Code:

---

while(fgetc(stdin)!='\n');

---

addressed that issue?

Code:

---

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

int main(void)
{
        char size[3];
        int a;
        while(1)
        {
                A : printf("Please enter how many words you want: ");
                fflush(stdout);
                for (a=0; a<3; a++)
                {
                        size[a]=fgetc(stdin);
                        if (size[0] == '\n')
                        {
                                printf("Input is empty\n");
                                goto A;
                        }
                        if (atoi(size) > 100)
                        {
                                printf("Input is too long\n");
                                while(fgetc(stdin)!='\n');
                                goto A;
                        }
                        if (size[a] == '\n')
                                break;

                }

                break;


    }
    printf("You want %d words.", atoi(size));

    return 0;

    }

---

Any help would be great thanks

This is irrelevant to your question, but why do you have a while(1) loop that breaks on the first iteration? Why have a loop at all? Instead of using goto you could just break out of the for loop instead then.

Maybe you want to get a string using fgets (see the FAQ) then convert that to an integer? Seems like it would be a whole lot simpler; although I think you would have to chop the \n char off the end of it first.

You aren't passing atoi() a properly null-terminated string.

Quote:

---

Originally Posted by arpsmack

You aren't passing atoi() a properly null-terminated string.

---

Meaning?

you need to add '\0' char at the end of the string so the atoi will know where to stop parsing

why you do not use fgets?

Quote:

---

Originally Posted by Iconate

I thought the command;

Code:

---

while(fgetc(stdin)!='\n');

---

addressed that issue?

---

This doesn't address your real question, but the line of code listed above is wrong. If you reach EOF before seeing a newline, in other words, if the last line of input has no newline on it, then this loop will spin infinitely. fgetc() will repeatedly return EOF, and EOF is not equal to '\n', so this never breaks. Instead, use:

Code:

---

while((ch = fgetc(stdin)) != EOF && ch != '\n')
    ; /* I usually place empty statements on their own line, to make it explicit that it's not a mistake. */

---