Question

Why do these 2 pieces of code yield different outputs?

    $a = 3;
    ($a == 4) and print "But I wanted apple, cherry, or blueberry!\n" ;

gives No program output but

    $a = 3;
    print "But I wanted apple, cherry, or blueberry!\n" and ($a == 4);

gives: But I wanted apple, cherry, or blueberry!

Answer 1

Because and is a so-called “short circuit” operator. Meaning that if you have condition1 and condition2, then the first condition is evaluated, and only if the first condition returns true is the second condition evaluated.

So, in

$a = 3;
($a == 4) and print "But I wanted apple, cherry, or blueberry!\n" ;

the condition $a==4 is false and so the print statement isn’t evaluated.

However, in

$a = 3;
print "But I wanted apple, cherry, or blueberry!\n" and ($a == 4);

The print statement does its thing and returns true. The second condition is evaluated (which is obviously false), but the printing is already done.