READ - Read a file

Basic form

READ DATASET dsn INTO f.

Addition

... LENGTH len

Effect

Reads a record from the sequential file specified in dsn (a field or a literal) and stores it in the field f (usually a field string).

Binary mode (addition IN BINARY MODE in the OPEN DATASET statement:

Read from file in length of field f .

Text mode (addition IN TEXT MODE in the OPEN statement):

Read a line.

If the specified file is not open, READ DATASET attempts to open the file dsn ( IN BINARY MODE FOR INPUT or with the specifications of the last OPEN command for this file). Any errors result in the termination of the program.
To read all the records in a file, you are recommended to place READ DATASET in a DO loop that you leave with EXIT .

The return code value is set as follows:

SY-SUBRC = 0 Record read from file.
SY_SUBRC = 4 End of file reached.

Example

Define the field string REC :


DATA: BEGIN OF REC,
        TEXT(30),
        NUMBER TYPE I,
      END OF REC.

Read the file "/usr/test":


DO.
  READ DATASET '/usr/test' INTO REC.
  IF SY-SUBRC <> 0.
    EXIT.
  ENDIF.
  WRITE: / REC-TEXT, REC-NUMBER.
ENDDO.

Notes

You can use TRANSFER to output records to a sequential dataset.

The format of file names depends largely on the operating system. You can access portable programs by using the function module FILE_GET_NAME which returns the physical name for a given logical file name.

Addition

... LENGTH len