RPG ILE %BIF (Built In Function)
I always forget the differences between %EOF, %EQUAL and Not %Found when writing native file I/O in RPG ILE Programs. Sometimes a file record is %found and sometimes its not. Even after all these years I still scratch my head about which one is which.
I know, I know – I should be using SQL right? SQL does things differently so these problems don’t bite us – but us crusty old time RPG chaps still have a secret soft-spot for good old fashioned chains don’t we?
I tend to copy blocks of code when writing source, it’s all too easy to copy a block of logic doing a subfile readc and change it to a chain without changing the %EOF to a %found. Which is exactly what I’ve been doing today. Of course, this ends up with chains looking for %EOF which compiles just fine. Grrrrr.
Since chain doesn’t necessarily set the file pointer to “end of file” sometimes I execute the NOT %eof( ) logic. Bloody annoying and not easy to spot a simply typo like this.
Must remember:
- %found is for chains
- %eof for reads
- %equal for setll
So, here is a quick little cheat sheet of which built in function to use with which command:
- Chain – %Found
- Check – %Found
- CheckR – %Found
- Delete – %Found
- LookUp – %Equal, %Found
- Read – %Eof
- ReadC – %Eof
- ReadE – %Eof
- ReadP – %Eof
- ReadPE – %Eof
- Scan – %Found
- SetGT – %Found
- SetLL – %Equal, %Found
- Write (subfile only) – %Eof
One further note – SETLL checking for %found means it positioned before the key but %EQUAL means it found the exact key.
