Thread: Read write problem

I try to read from a file and to write to another file an arbitrary number of bytes

Code:

int main (int argc, char* argv[]) 

{
  FILE * pFileR;
  FILE * pFileW;
  char buffer[32];
  pFileR = fopen (argv[1], "rb");
  strcpy (writeFileName, "new_");
  strcat (writeFileName, argv[1]);
  pFileW = fopen (writeFileName, "w");
  if (pFileR==NULL || pFileW==NULL) 
      {
                    if(pFileW!=NULL) fclose(pFileW);
                    if(pFileR!=NULL) fclose(pFileR);
                    fputs ("File error", stderr); 
                    exit (1);
      }
 for(i=0; i<20; i++)
      {
      fread (buffer, 1, sizeof(buffer), pFileR);
      fwrite (buffer, 1, sizeof(buffer), pFileW);
     }
  fclose(pFileR);
  fclose(pFileW);
  return 0;
}

The first file is bigger than the number of bytes I read from it. Then I use a file compare utility to compare the files. The problem is that only the first 338 bytes are ok. After that I get an extra space(ASCII) offset and of course the rest of the file is diferent. No matter the size of buffer, I always get only the first 338 bytes correctly written.

Writing in text mode was the problem indeed. Now it's ok, the files are indentical as expected. Thanks vart.

I know I should check the number of bytes read and written. That's the way I wrote the code in the first place but then it gave me this error and I simplified the code in order to find the problem. The problem was that in text mode after 338 bytes a linefeed character was found that was exchanged with a linefeed + carriage return.

Problem solved, thank you all!