bad fcanf() format

**mirekgn** · 03-28-2010

Hello.

this is code of piece of my program:

Code:

  FILE *fp;
  if((fp = fopen("prog_conf.txt", "r")) == NULL)
  {
    printf ("\nNie mogę otworzyć pliku prog_conf.txt do zapisu!");
    return NULL;
  }
  printf ("\nPlik otwarto!\n");

  while( fscanf(fp,"%s#%s",optionName,optionValue) != EOF)
  {
    printf("\n%s : %s",optionName,optionValue);
  }

  fclose(fp);

and here is structure of prog_conf.txt file:

Code:

log_file#log.txt
mysql_server#localhost
mysql_user#root
mysql_pass#asd
mysql_db#schoolSubjects
defaultnumquest#5

If I use format as %s#%s then whole first part of file line is writing to variable optionName. I don't know what is wrong. I want to write first part of line(before #) to variable optionName and secound part of line (after #) to variable optionValue. Can you help me with that?:/

**MK27** · 03-28-2010

The problem is %s will include #. Try this one:

Code:

"%[^#]#%s"

[] indicates a set. Usually they are inclusive, eg [0-9,a-z] will capture any combination of digits and non-caps. ^ indicates exclusion, so [^#] will capture anything, not include #.

I believe since you are using fscanf directly on the file you may end up with newlines getting left in the buffer (they are not eaten by %s, so %[^#] may pick them next. If that happens use %*c at the end of the template (* discards).

Code:

"%[^#]#%s%*c"

**vart** · 03-28-2010

%s stops reading on whitespace

you want to stop reading on #

Code:

%[^#]#%s

something like that should work

of cause adding width modifier to prevent buffer overrun would be safe thing to do...

**mirekgn** · 03-28-2010

Code:

%[^#]#%s

Thank you! It is working. But now there is a one little problem. In variable optionName as the first char there is writing char of the new line \n. and when i print this variable, it is in the new line. Is there in c a function like a trim() from php, or something like that?

**MK27** · 03-28-2010

Originally Posted by mirekgn

Is there in c a function like a trim() from php, or something like that?

No, but you could write one quite easily. However, that is not necessary. If you had read more than just the very last post, you should have noticed:

Originally Posted by MK27

I believe since you are using fscanf directly on the file you may end up with newlines getting left in the buffer (they are not eaten by %s, so %[^#] may pick them next). If that happens use %*c at the end of the template (* discards).

Code:

"%[^#]#%s%*c"

The '\n' you are getting at the beginning is left over from the end of the previous line, so if you discard it in the first place it won't be there later. %c is a single character (such as '\n', which is not included in %s) * indicates this item does not go into a variable but gets thrown away.

**mirekgn** · 03-28-2010

yeah! Thank you so much.
format:

Code:

%[^#]#%s%*c

is working.

**mirekgn** · 03-28-2010

And what now when I have line in file like that:

Code:

biologia#Nazwa nauczyciela#Tkanki i bakterie

Format above is not working:/ I tried to change this format analogously to format above but I do it wrong. Can you write me correct format for writing 3 variables?

**mirekgn** · 04-10-2010

Can someone help me with that?
I think the problem is that %s stops reading on whitespace but I don't know how to do it in C language.

**quzah** · 04-10-2010

%[ ...scan set... ] = put between brackets what you want to scan for
start it with ^ if you want to scan for stuff NOT in the brackets
%*c = skip one character (the * says to not store what you're scanning for)

Quzah

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