Re: C code... file reading(twice)... strange problem!

At 2005-03-23 06:12:17 -0800, rohitsz2-/[email protected] wrote:
>
> > > ...
> > > 		fread(&val,sizeof(long),1,fs);
> >                   ^^^^
> > Similarly, you want just "val" here. (I note, however, that you're
> > overwriting your loop counter; and it works only because the value
> > you read from the file is the value of the loop counter anyway.)
> 
> done that...( i am not overwriting my loop counter(ie
> i=val, i am not doing any such thing... so where am i
> overwriting?!, kindly point out!)
> though i must tell when i wrote into the file with    

When you call fread above, it reads 1*sizeof(long) bytes from fs, and
writes it to *val. Since val == &i, it overwrites the value of i. The
only reason it works is because the value of i just happens to be the
same as the value read from the file (because that's how you wrote it
in the first loop).

> > > 			for(i=0;i<n;i++)
> > > 			{/* fread reads same value every time!*/
> > > 				fread(&val,sizeof(long),1,fp);
> >                                   ^^^^
> > First, you want just "val" here. Second, val is uninitialised here,
> > so this code just won't work. Try making val actually point to
> > something.
> 
> done this too...(i can't understand, why to make val
> point to something..? i am reading anything before
> writing something in it!)

Huh? val must point to valid storage for 1*sizeof(long) bytes for fread
to work.

-- ams