CT320 IQ 08
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Sigils
In Perl, which sigil indicates an array?
@
$
%
#
&
- I don't know what the @$%#& a “sigil” is!
@ = array. Think of @ as the a in array.
Declaration
In Perl, how do I declare a scalar?
my zot;
int zot;
my $zot;
int $zot;
- You can’t.
We don’t give types to our variables, so int is out.
A scalar always has a $ with it.
Arguments
In Perl, how are arguments passed to a function?
sub foo(alpha, beta, gamma)
sub foo($alpha, $beta, $gamma)
- Implicitly, in @_.
- Via some other agreed-upon global array.
Arguments are passed in @_.
Named parameters ($alpha, $beta) are possible, but they’re an
experimental feature that you have to explicitly enable.
$_
In Perl, what does $_ mean?
- It’s just a scalar with an odd name.
- It’s related to @_ somehow.
- Sometimes, implicitly set in a
for loop.
- Sometimes, implicitly set in a
while loop.
$_ is a scalar with an odd name, but not “just” that.
It’s implicitly set in for (1..3), and in while (<FH>) loops.
Array
In Perl, how do I concatenate @a and @b into @c?
@c = @a + @b;
@c = (@a, @b);
@c = @ab;
@c = @a, @b;
@c = @a; push @c, @b;
A does addition, in scalar context, of the sizes of @a and
@b. @ab is a brand-new variable.
Either B or E will work, but B is easier to read.
What will this code display?
if ("My dog has fleas" =~ /(d*g)/) {
print "I matched “$1”\n";
}
else {
print "nope\n";
}
I matched “g”
I matched “nope”
I matched “dog”
I matched “g”
- It will throw an exception.
nope
Sycophancy
What is the best language ever?
- Perl
- Perl
- Perl
- Perl
- Perl
- Python