Thread: problem re-opening file

I've been trying to solve this problem for a while

Code:

char templine[256],filename[256];
.
FILE *ofp;
ofp=fopen(filename,"r");
.
.
.
fclose(ofp);
ofp=fopen(filename,"w+");
fprintf(ofp,"%s\n",templine);

for some reason the file does not close and reopen correctly. By ading lots of printf statements, after the line
ofp=fopen(filename,"w");

ofp is NULL. however filename is unchanged from the initial opening. This means that the subsequent printf statments will obviously fail.

I don't see what the problem is here


the situation is that I've read out the contents of ofp, editing them on the way, and placed it all in a temp file. Now I just need to clear ofp and copy everything back in. (which is why I'm reopening it, as openeing in "w" clears the file). if there's a more reliable/cleaner way to do this please tell me. sorry if this is something obvious I've overlooked.

thanks
-Mark

Maybe your system can provide you with a reason if you add something like this.

Code:

ofp=fopen(filename,"w+");
if(ofp != NULL)
{
   /* write to the file */
}
else
{
   perror(filename);
}

You might also check the return value of fclose.

using the line:

printf("%d\n",fclose(ofp));

fclose is returning 0 (successful).


the perror statement gives "permission denied".

I'd assume this means the file ir read-only or already open, but as the file was successfully closed, this leaves me a little confused


thanks
-mark

oops...

it is because the file was read only... I just got confused over which file was actually being opened and didn't realise.

Thanks for helping me get that sorted out

-mark