File Write in PHP:
  Different modes of file to operated on a file, you have to open a file with one of these modes.                          Mode             Description                                                         'r'                           Open for reading only; place the file pointer at the              beginning of the file.                                                'r+'                          Open for reading and writing; place the file pointer at              the beginning of the file.                                                 'w'                          Open for writing only; place the file pointer at the              beginning of the file and truncate the file to zero length.              If the file does not exist, attempt to create it.                                                 'w+'                          Open for reading and writing; place the file pointer at              the beginning of the file and truncate the file to zero...