Summary

• when some amount of data is to be stored in a file, the file is organized in the form of a table with rows representing records and columns representing fields.
• The C language treats files as just a stream of characters and accordingly allows input and output in strings of characters.
• Functions re available for single character as well as multiple character I/O from files.
• FILE is a datatype defined in the header file stdio.h.
• The standard library function used for opening a file in C is
  fopen (file-nane, mode)
• Mode specifies the way in which a file is to be opened, There are 6 modes in which a file can be opened –
• read-only
• write-only
• append
• read + write
• write + read
• read + append
• Two functions –
  fgetc()   and
  fputc
  facilitate character I/O with files
• EOF is a constant defined in the header file stdio.h, it indicates end of file.
• fopen (), when unsuccessful, returns a NULL value.
• The function fclose () is used to close opened files.
• stdin, stdout and stderr are FILE type pointers declared in the header tile stdio.h. They refer to the standard input device(keyboard), standard output device(VDU) and standard error device(VDU) respectively.
• Two functions facilitate line VO with files –
  fgetc()
  fputc()
• The Two functions
  fprintf()   and
  fscanf()
  facilitate formatted /O with files. They are similar to printf() and scanf (). but for one additional parameter, the file pointer.
• Random access in files is possible with the function fseek() .
• The function rewind () positions the pointer at the beginning of the file.
• Whole records can be read from or written into a file using the functions fread() and fwrite().