print +("a", "b")[1];
[download]

It stems from the fact that print, if immediately followed by a lparen (with \s* in between), assumes that the lparen and its matching rparent enclose print's entire parameter list. You can clear up print's "confusion" by adding another set of parens to enclose the parameter list:

print( ("a", "b")[1] );
[download]

print ("a", "b")[1];

does not work, you need an extra pair of ():

print (("a", "b")[1]);

but

print qw(a, b)[1];

works fine without ().

The book I am reading(http://www.perl.org/books/beginning-perl/) says print has higher precedence than 1. But this does not work in the second example with "qw" so I am confused.

i mean print has higher precedence than [1]. But this is not true in the second example.

Let me try to explain the question better :

("a", "b") and qw(a, b)

are two equivalent ways of defining a list, so both examples should not work(because print has higher priority than [1]):

print ("a", "b")[1];
print qw(a, b)[1];
[download]

But for some reason only the first one does not work...

From the bottom of SoPW:

for [ use [
for ] use ]

- Miller

Um, yeah, but you left out the bit that says "Outside of code tags, you may need to use entities for some characters." A better answer would have been to put <code> tags around the chunks of perl code.

Enclose code in <code> </code> tags. See the bulleted help at the bottom of the preview page (although you can use &#91; and &#93; for [ and ] if required outside a code context).

---

DWIM is Perl's answer to Gödel

thank you all for your responses!