Thread: Not allowing numbers to be entered.

how about isalpha() ?

> just make sure your complier supports fflush(stdin) ,just like mine.
Just make sure you learn how to do it properly - then the "works for me compiler" issue becomes irrelevant.

> if(numberofmeters<0||numberofmeters>100000)goto retry;
1. Don't use goto
2. If scanf fails, then the result is at best unmodified and at worst undefined. Either way, your test is horribly broken.

> void main()
Ditto for this - use int main and be compatible with the whole universe.


All of you need to read http://faq.cprogramming.com/cgi-bin/...&id=1043284385

Especially this section:

To clear the input buffer, you have to read through the input until there is no more. Sometimes you'll see people recommending the use of fflush(stdin), but this is undefined behaviour, and is therefore bad practice. Instead, use something like the following, a looping input function that eats characters until the desired end of line marker is reached:

Code:

while (getchar() != '\n');

And this:

Code:

#include <stdio.h> 

int main(void)
{
  int temp;
  
  printf ("Input your number: ");

  while (scanf("%d", &temp) != 1)
  {
    while (getchar() != '\n');
    printf ("Try again: ");
  }

  printf ("You entered %d\n", temp);
  
  return(0);
}

how about isalpha() ?

isdigit() might work.

But it would be easier to use scanf() or something else covered in the FAQ.

> only the c standard says that its behavior should be undefined
That's the only thing that matters.
What your tin-pot compiler allows is entirely up to whoever wrote the compiler.

I see a lot of responses to my posts are "thanks, that worked". Why is that, because I stick to the standard, which works EVERYWHERE.

I see a lot of responses to your posts being "but I don't have .... magic compiler specific function".

> LONG LIVE THE C LANGUAGE. (lmao)
Next stop - loonyville - please depart the train now if you don't want to go there.

Mine works all the time.

Yours only works so long as you or the person you're talking to use the same compiler.
Come upgrade time, you'll both have to learn the same stuff all over again.

Originally Posted by qqqqxxxx

so why didnt the rest of your class have problems?

Because they were all using the same compiler. I was the only one using a different complier.

Actually, to be more accurate, we were all, in theory, using the same compiler (GCC) but, for some reason that I still do not fully understand, it worked on the Windows machines using Dev-C but didn't work for me running MacOSX and Xcode.

I suppose that, logically, the only explanation is that, despite the fact that both types of computer are supposed to be using GCC (at least that is what my teacher, who has proven to be somewhat unreliable, says), there is a subtle difference between the two compilers that I do not know about.

EDIT - Yes, I do want to stick to the standard because I want to learn C. I do not want to learn some non-standard, non portable version of C that only SOME compilers can understand. I want my code to be able to complie on ALL compilers. That's why standards exist.

Originally Posted by qqqqxxxx

lmao how could u forget,ritchie and kernigham,,THE VERY FOUNDERS OF THE LANGUAGE,
AND do u have relations in the ANSI C commitee?

and r u going to throw your neat 4 word code rite in your professors face and tell him that u r smarter than him?

Ok, I do know who K&R are, I just don't understand what you are trying to get at. Your posts are terse to the point of being incomprehensible.

Perhaps you would like to expand on your posts so that they are clearer.

EDIT - In response to your question, I am not going to throw any code at anyone. I never suggested I was. Also, I have no idea what "4 word code" you are talking about.

Secondly, it is not up to me to say who is right and who is wrong. The standard will do that for me.

Originally Posted by qqqqxxxx

lmao ,dont mind,just amusing myself,now delete all your replies just like i am going to do to mine

I think I'll leave mine thanks

EDIT - Why go to all the trouble of posting 8 or 9 posts aking me questions and making obscure allusions to the benefits/pitfalls of standard and non-standard C only to delete them all almost immediately afterwards.

What a waste of time!