Assistance in understanding sqr logic

Question

Hello, I am new to learning how to develop sqr programs within PeopleSoft. I've been going through some programs we are utilizing and wanted to see if someone could help provide clarification with what the below snippet of code is doing in this While loop.

 if $path != ''
   let $Archive_File = $path || 'ARCHIVE\' || $filename || $Curr_Date || '.dat'
   open $Out_File  as 1  for-reading record=450:vary status=#fileread
   open $Archive_File as 2  for-writing record=450:vary status=#filewrite
   While 1
     if #END-FILE
        break
     else
        read 1 into $Current_Line:999
        write 2 from $Current_Line
    end-if    
 End-While
 close 1
 close 2
end-if

I'm trying to understand if the WHILE statement is evaluating the "$Out_File as 1" as the logical expression, or is 1 being evaluated as the value of the variable #END-FILE (As I understand this variable is set to either 0 or 1).

Answer 1

In addition to the file name, the open command takes a number as a parameter which it uses as a handler for the file. In your example, two files are being opened.

The WHILE 1 statement doesn't have anything to do with file 1. Here 1 means true, instead of 0 for false. So 1 is always true, creating an endless loop unless something within the loop breaks out if it, which in this case is the BREAK command.

The #END-FILE variable contains FALSE when the file cursor is not at EOF, and a TRUE when the the file cursor is at EOF.

An alternative, which uses less lines of code and is easier to understand might look like this:

if $path != ''
  let $Archive_File = $path || 'ARCHIVE\' || $filename || $Curr_Date || '.dat'
  open $Out_File  as 1  for-reading record=450:vary status=#fileread
  open $Archive_File as 2  for-writing record=450:vary status=#filewrite
  While Not #END-FILE
    read 1 into $Current_Line:999
    write 2 from $Current_Line
  End-While
  close 1
  close 2
end-if

Answer 2

Its a true loop, it will go there until reach a BREAK. In this case if #END-FILE is true, the loop will break.