scalar
EXPR
This pseudo-function may be used within a
LIST
to force
EXPR
to be
evaluated in scalar context when evaluation in list context
would produce a different result.
For example:
local($nextvar) = scalar <STDIN>;
prevents
<STDIN>
from reading all the lines from
standard input before doing the assignment, since assignment to a
local
list provides a list context. (Without the use of
scalar
in this example, the first line from
<STDIN>
would still be assigned to
$nextvar
, but the subsequent lines would be read and thrown
away. This is because the assignment is being made to a list - one that
happens to be able to receive only a single, scalar value.)
Of course, a simpler way with less typing would be to simply leave the parentheses off, thereby changing the list context to a scalar one:
local $nextvar = <STDIN>;
Since a
print
function is a
LIST
operator, you have to say:
print "Length is ", scalar(@ARRAY), "\n";
if you want the length of
@ARRAY
to be printed out.
One never needs to force evaluation in a list context, because any operation that wants a list already provides a list context to its list arguments for free. So there's no list function corresponding to scalar .
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