Passing array member as a parameter

**stumpster123** · 03-28-2005

In my main function I have an array of File pointers like this:

Code:

FILE *fInfile[MAXFILE]

and my functions header is

Code:

int read_info(FILE *fA, FILE *fI);
{
.
.
.
  if((fI = fopen(szFilename, "w")) == NULL)
    {
      fprintf(stderr, "Could not open the input file %s.\n", szFilename);
      exit(1);
    }
.
.
}

I call the function with the following

Code:

iSize[iTemp] = read_info(fArchive, fInfile[iTemp]);

where iTemp is the current file i want to write open

However when i go to use the file pointers they are all null. I have gotten the program to work correctly but not in the way i want too by sending iTemp as a parameter and the entire array instead.

I tried using double asterisks to send the dereference the pointer but I could not get it to work correctly could someone please help me understand what is wrong with this code.

Thanks.

**quzah** · 03-29-2005

Have you actually opened every file with fopen? You know, something like:

Code:

char buf[BUFSIZ] = {0};

for ( i = 0; i < MAXFILE; x++ )
{
    sprintf( buf, "filename%03d.dat", i );
    fInfile[ i ] = fopen( filename, "r" );
    if( fInfile[ i ] == NULL )
    {
        ...fopen failed...
    }
}

Quzah.

**stumpster123** · 03-29-2005

Yeah that is what read info is doing before it reads anything. It opens the file and uses the file pointer that is sent from main function. I am using an array so the function call is in a for loop that will open all the files. But when i use the function the array in the main function remains all NULL instead of pointing to the files that were opened in the read function.

**Dave Evans** · 03-29-2005

Originally Posted by stumpster123

It opens the file and uses the file pointer that is sent from main function.
...
But when i use the function the array in the main function remains all NULL instead of pointing to the files that were opened in the read function.

You could try this:

Change read_info() to this

Code:

int read_info(FILE *fA, FILE **fI);

Call it like this:

Code:

iSize[iTemp] = read_info(fArchive, &fInfile[iTemp]);

And inside read_info, open the file like this:

Code:

  if((*fI = fopen(szFilename, "w")) == NULL)

Now, the value gets passed back to the calling program.

Regards,

Dave

***Note*** My original post had a "typographical" error, which has been corrected here.

**stumpster123** · 03-29-2005

Thanks dave that worked perfectly.

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