Source : Free On-Line Dictionary of Computing

loop through
     
        To process each element of a list of things.  "Hold on, I've
        got to loop through my paper mail."  Derives from the
        computer-language notion of an iterative loop; compare "cdr
        down" (under {cdr}), which is less common among C and Unix
        programmers.  ITS hackers used to say "IRP over" after an
        obscure pseudo-op in the MIDAS PDP-10 assembler.
     
        [{Jargon File}]