比較操作符，正如它的名字所示，允許您比較兩個值。
Table 7-4. Comparson Operators（表7-4 比較操作符）
example name result?/FONT>
$a == $b Equal?/FONT> True if $a is equal to $b.?/FONT>
$a != $b Not equal True if $a is not equal to $b.?/FONT>
$a < $b Less than?/FONT> True if $a is strictly less than $b.?/FONT>
$a > $b Greater than?/FONT> True if $a is strictly greater than $b.?/FONT>
$a <= $b Less than or equal to?/FONT> True if $a is less than or equal to $b.?/FONT>
$a >= $b Greater than or equal to?/FONT> True if $a is greater than or equal to $b.
