fopen help.

Hi,

I am having a problem with fopen. I have searched the forum but with no luck.

i am trying to open a binary file using fopen. I am using Borland C++ 3.1 and it cannot open the file. fopen gives a NULL pointer. When opening the same program in Turbo C++ for Windows it seems to work correctly.

the file is stored in the follow location

J:\dsaaIII\ass1\Program 3\DATABASE.BIN

This is my code

Code:

char fname[]="J:\\dsaaIII\\ass1\\Program 3\\DATABASE.BIN";

FILE * ptrFile;

ptrFile=fopen(fname, "rt");

if(ptrFile==NULL){
         printf("\n Error Opening Database File!\n\n Please Press Any Key To Continue >");
         getch();

         clrscr();

         return 0;
}

fread( lastRecordID, sizeof(int), 1, ptrFile );

fclose(ptrFile);

The above is a code snippet. The actual fuction is more complex. however it should still be able to open the file. which it is clearly failing.

Thanks in advance.

Chris

You probably want to open the file in binary mode. Use "rb" instead of "rt" as your second parameter to fopen()

>J:\\dsaaIII\\ass1\\Program 3\\DATABASE.BIN
Borland C++ 3.1 probably doesn't support directories/filenames longer than eight characters. Under DOS, "Program 3" would probably equate to a name like "Progra~1".

Turbo C++ might only support 8.3 filenames. Or else you might need quotes:

Code:

char fname[]="\"J:\\dsaaIII\\ass1\\Program 3\\DATABASE.BIN\"";

If you support only 8.3 filenames, find out the DOS name for "Program 3".

Under DOS, "Program 3" would probably equate to a name like "Program~1".

Under Windows-based DOS, you mean, like Windows 98. Windows XP will give it a random 8.3 name. To find out what it is, type this from a command prompt:

Code:

C>J:

C>cd \dsaaIII\ass1\

C>dir "Program 3"

>Windows XP will give it a random 8.3 name.
Are you sure? Because under the Windows XP version I'm using it doesn't appear to be random.

Hey, thanks for your help so far.

I got...

Directory of J:\dsaaIII\ass\Program 3

.... does this mean its ok??

Chris

Oops, my mistake. Use

Code:

C>dir program*

instead, and it might print something like

Code:

qwerty <DIR> 11-11-11 12.00p Program 3

The "qwerty" part is the part you want. See what it is.

>Windows XP will give it a random 8.3 name.
Are you sure? Because under the Windows XP version I'm using it doesn't appear to be random.

Windows 2k/2k3/xp Long Filename Truncation

*edit*DWKS: if you try what he says, you see that the file names don't end up looking like that, copy of text document.txt, turns into co0dfb~1.txt for example.

I thought it would be like that, too, but it seems random to me.

i have just tried that but cannot seem to make it display anythin random.

Chris

Can you post the output of the dir command?

Unless the double-quote thing solved the problem, in which case don't bother.

Thanks for all your help.

I have got it working now.

It was because i was typing the wrong thing into dos. I have got the shorter name for the folder Program 3 and it seems to work ok now.

Thanks again

Chris

>I thought it would be like that, too, but it seems random to me.
Well I wasn't using the dir command, but instead was using a 16-bit windows program, and it wasn't coming up random. Tomorrow I'll try the dir command and see what it displays.

Ok, I tried the dir command on my XP machine, and the 8.3 filenames are not random. Maybe someone else can try it on XP and see what they get.

I would expect it to be non-random. But my link seems to suggest otherwise.