FORTRAN 77 Language Reference

Execution

Execution proceeds as follows:

  1. The file associated with the specified unit is determined.

    The format, if specified, is established. The file is positioned appropriately prior to the data transfer.

  2. If the input list is not empty, data is transferred from the file to the corresponding items in the list.

    The items are processed in order as long as the input list is not exhausted. The next specified item is determined and the value read is transmitted to it. Data editing in formatted READ is done according to the specified format.

  3. In the third and fourth forms of namelist-directed READ, the items of the specified namelist group are processed according to the rules of namelist-directed input.

  4. The file is repositioned appropriately after data transfer.

  5. If ios is specified and no error occurred, it is set to zero.

    ios is set to a positive value, if an error or end of file was encountered.

  6. If s is specified and end of file was encountered, control is transferred to s.

  7. If s is specified and an error occurs, control is transferred to s.

There are two forms of READ:

READ f [, iolist]

READ([NML= ] grname)

The above two forms operate the same way as the others, except that reading from the keyboard is implied.

Execution has the following differences:

If u specifies an external unit that is not connected to a file, an implicit OPEN operation is performed equivalent to opening the file with the options in the following example:


       OPEN(u,
FILE='FORT.u', STATUS='OLD', ACCESS='SEQUENTIAL', 
&              FORM=fmt
)

Note also: