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Transfers a record of data from an input device to the user's
data area. Syntax | |
transfercount:=FREAD(filenum,buffer,length); |
Use | |
Use the FREAD intrinsic to read a logical record from a file
to the user's data area. For asynchronous devices, this
implies the transfer of data (one record at a time) from an input
device, usually a terminal, to the data area. Condition codes are
used to indicate completion status and should be checked after each
read, whether you are using NOWAIT I/O or normal I/O processing.
Read timeouts or timers must be set prior to an FREAD by calls to
the appropriate FCONTROL functions. When the logical end-of-data is encountered during a read,
CCG is returned to your process. The end-of-data is indicated by
a hardware end-of-file; on $STDIN,
by any record beginning with a colon (:); or on $STDINX
by :EOD. Functional Return | |
- transfercount
16-bit signed integer (assigned functional return) Assumes a value corresponding to the length of the information
transferred. If the value specified in the length
parameter of the call was a positive number, the value returned
in transfercount is positive, and represents
a halfword count. If the value specified in the length
parameter was negative, the value returned in transfercount
represents a byte count. FREAD always returns a zero if you specified NOWAIT I/O in
FOPEN or HPFOPEN. In this case, the actual record length is returned
in the length parameter of the IOWAIT or
IODONTWAIT intrinsic.
Parameters | |
- CCE
The information was read. - CCG
The logical end-of-data was encountered during reading. - CCL
The information was not read because an error occurred:
a terminal read was terminated by a special character or timeout
interval, as specified in the FCONTROL intrinsic.
Additional Discussion | |
See Accessing Files Programmer's Guide.
See also discussion of IOWAIT and IODONTWAIT in this manual. |
