Perl 5 version 14.3 documentation
Interprets EXPR as a hex string and returns the corresponding value. (To convert strings that might start with either
0b, see oct.) If EXPR is omitted, uses
Hex strings may only represent integers. Strings that would cause integer overflow trigger a warning. Leading whitespace is not stripped, unlike oct(). To present something as hex, look into printf, sprintf, and unpack.