Programming Perl, 4th Edition

Equality Operators

The equality operators listed in Table 3-6 are much like the relational operators.

Table 3-6. Equality operators

Numeric	String	Meaning
==	eq	Equal to
!=	ne	Not equal to
<=>	cmp	Comparison, with signed result
~~	~~	Smartmatch

The equal and not-equal operators return 1 for true and "" for false (just as the relational operators do). The <=> and cmp operators return –1 if the left operand is less than the right operand, 0 if they are equal, and +1 if the left operand is greater than the right. Although the equality operators appear to be similar to the relational operators, they do have a lower precedence level, so $a < $b <=> $c < $d is syntactically valid.

For reasons that are apparent to anyone who has seen Star Wars, the <=> operator is known as the “spaceship” operator.

The ~~ operator is described in the next section.