On May 29, 2014, at 1:20 PM, James Kerwin wrote: > Hello all, long time lurker, first time requester... > > I have a Perl exam tomorrow and came across a question that I just cannot > find an answer to (past paper, this isn't cheating or homework etc.). > > Explain the difference between: > > ($test)=(@test); > > And > > $test=@test; > > If anybody could shed any light on this I'd be very grateful.
The difference is the "context" of the assignment: "scalar" or "list", and how @test (or (@test)) is evaluated in that context. In the first statement ($test) = (@test), the parentheses around $test in the left-hand side (LHS) of the assignment places the evaluation of the right-hand side (RHS) in list context. In list context, with two lists on either side of the assignment operator (=), assignment is made from each element on the RHS to the corresponding element on the LHS. Therefore, the one and only element on the LHS ($test) gets assigned the value of the first element of the RHS, and $test ends up with the value of $test[0]. In the second statement, the assignment is done in scalar context, and the RHS is evaluated in scalar context. A list evaluated in scalar context returns the number of elements in the list, and $test is assigned the value ($#test+1). Note that the parentheses around @test in the first statement are irrelevant. The context is list with or without them. Try it yourself: % perl -e '@t=qw(1 2 3);$t=@t;print qq($t\n);' 3 % perl -e '@t=qw(1 2 3);($t)=@t;print qq($t\n);' 1 % perl -e '@t=qw(1 2 3);($t)=(@t);print qq($t\n);' 1 -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
