3.2.131 scalar

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.