Relational Operators
Binary "<" returns true if the left argument is numerically less than
the right argument.

Binary ">" returns true if the left argument is numerically greater
than the right argument.

Binary "<=" returns true if the left argument is numerically less than
or equal to the right argument.

Binary ">=" returns true if the left argument is numerically greater
than or equal to the right argument.

Binary "lt" returns true if the left argument is stringwise less than
the right argument.

Binary "gt" returns true if the left argument is stringwise greater
than the right argument.

Binary "le" returns true if the left argument is stringwise less than
or equal to the right argument.

Binary "ge" returns true if the left argument is stringwise greater
than or equal to the right argument.

Equality Operators
Binary "==" returns true if the left argument is numerically equal to
the right argument.

Binary "!=" returns true if the left argument is numerically not equal
to the right argument.

Binary "<=>" returns -1, 0, or 1 depending on whether the left argument
is numerically less than, equal to, or greater than the right argument.
If your platform supports NaNs (not-a-numbers) as numeric values, using
them with "<=>" returns undef. NaN is not "<", "==", ">", "<=" or ">="
anything (even NaN), so those 5 return false. NaN != NaN returns true,
as does NaN != anything else. If your platform doesn't support NaNs
then NaN is just a string with numeric value 0.

perl -le '$a = "NaN"; print "No NaN support here" if $a == $a'
perl -le '$a = "NaN"; print "NaN support here" if $a != $a'

Binary "eq" returns true if the left argument is stringwise equal to
the right argument.

Binary "ne" returns true if the left argument is stringwise not equal
to the right argument.

Binary "cmp" returns -1, 0, or 1 depending on whether the left argument
is stringwise less than, equal to, or greater than the right argument.

Binary "~~" does a smart match between its arguments. Smart matching is
described in "Smart matching in detail" in perlsyn.

"lt", "le", "ge", "gt" and "cmp" use the collation (sort) order
specified by the current locale if "use locale" is in effect. See
perllocale.