Programming Perl, 4th Edition

Relational Operators

Perl has two classes of relational operators. One class operates on numeric values, the other on string values, as shown in Table 3-5.

Table 3-5. Relational operators

Numeric	String	Meaning
>	gt	Greater than
>=	ge	Greater than or equal to
<	lt	Less than
<=	le	Less than or equal to

These operators return 1 for true and "" for false. Note that relational operators are nonassociating, which means that $a < $b < $c is a syntax error.

In the absence of locale declarations, string comparisons are based on the numeric Unicode codepoint order of each character in the string. With a locale declaration, the collation order specified by the locale is used. These legacy, locale-based collation mechanisms do not interact well with the Unicode collation mechanisms provided by the Unicode::Collate and Unicode::Collate::Locale modules. It is better to use the modules, not locales. Codepoint order is not alphabetic order except in (unicameral) ASCII, so Perl’s string operators will produce alphabetic results only on legacy ASCII data, not on arbitrary text.