The problem is likely in your calling routine. Since $_ is a global, using it in any non-local context (like a loop variable in a loop that calls a subroutine) can be hazardous. You could fix your code by creating a local copy:

sub case_f {  local $_ = catfile( $TOP_DIR, $_[0], $_[1] ); print "The path is $_ "; $_ }

To answer the more general question addressed by your subject line, you can find many details in perlvar. Note that they cover exactly what I said above in the intro to that piece of documentation.

In reply to Re: $_ when does it get set ? by kennethk
in thread $_ when does it get set ? by smartnut007

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