The EXFMT operation performs the functional equivalent of a WRITE operation followed immediately by a READ operation. This operation can be used with a device (i.e., nondatabase) file only. Example 11.3 illustrates the use of the EXFMT operation.
Example 11.3: Retrieve and display a database record.
.....FFileName++IFEASFRlen+LKeylnKFDevice+.Functions++++++++++++++++++++++++++++ 0001 FCUSTINQ CF E WORKSTN 0002 FCUSTMAST IF E K DISK .....CSRn01Factor1+++++++OpCode(ex)Factor2+++++++Result++++++++Len++DcHiLoEq.... 0003 C INDEX CHAIN CustRec 71 0004 C EVAL NotFound = *IN71 0005 C IF NotFound = *OFF 0006 C EXFMT DSPCUST 73 0007 C ENDIF
In Example 11.3, a record from the CUSTMAST database file (line 2) is retrieved (line 3). The workstation file CUSTINQ (line 1) is written to and read from with the EXFMT (line 6). The DSPCUST workstation file format is used in factor 2 of the EXFMT operation.
When several workstation file formats are needed on the display, the additional formats must be written with the WRITE operation. The final format (the one after which an input operation is required) can be written to the workstation file with the EXFMT operation. This effectively performs a WRITE followed by a READ.