write statement the write

Question

WRITE Statement:

     The WRITE statement for a relative file has the format which is as shown below.

         WRITE  record-name   [ FORM   identifier ]

                                            [  ;   INVALID KEY  imperative statement  ]

At the time of the execution of WRITE statement, the file should be open either in the OUTPUT or I-O mode. For illustration, assume REL-OUTPUT AND REL-KEY are the record name and relative key data item name for a relative file opened in the I-O mode. Then, upon execution of the statements below:

MOVE     50  TO  REL-KEY.

WRITE REL-OUTPUT  INVALID KEY GO TO PARA-INVALID.

The record is written at the 50^th record location on the file.     

The imperative statement of INVALID KEY phrase is the execution in the situation as shown below:

(i)  When a try is made to write beyond the externally-defined boundaries of the file.

(ii) When a try is made to write in the record place that already contains a valid record.