Thread: can some please demonstrate fgets ?

Code:

char *ptr = NULL;

....

fgets(fname, sizeof(fname), stdin);
if((ptr = strchr(fname, '\n')) != NULL)
{
    *ptr = '\0';
}

Originally Posted by broli86

what if fgets returns a NULL ??

Then it failed. You probably want to quit at that point.

Originally Posted by broli86

and is it ok to write a else case which will print an error message incase the buffer overflowed ?

The buffer can't overflow. You're passing the size of the array, and fgets() knows not to overflow. This is why you're supposed to use fgets() over gets() in the first place!

Originally Posted by MacGyver

Then it failed. You probably want to quit at that point.

And it's a good idea to check for that before the strrchr(), as I doubt that strrchr() is "NULL-safe".

The buffer can't overflow. You're passing the size of the array, and fgets() knows not to overflow. This is why you're supposed to use fgets() over gets() in the first place!

I think broli is referring to when the input is not complete (that is, there is no '\n' at the end of the string - in which case the input was longer than expected - this PROBABLY needs to be dealt with - and as opposed to gets(), there is a possibility of fixing it here, because the application can check, rather than most likely just crashing!

So, if there is no \n at the end of the input, then the application received a string that was too long. Clear the input, e.g.

Code:

void clear_input(FILE *in)
{
    int ch;
    while((ch = fgets(in)) != '\n' && ch != EOF) ;
}

Then ask again (if the input is console, if the input is a file, then you probably just want to print an informative message and quit - that is, if you can tell the difference).

--
Mats

Originally Posted by matsp

And it's a good idea to check for that before the strrchr(), as I doubt that strrchr() is "NULL-safe".

Agreed.