If you were dealing with a mixture of binary (as 0b...), hexadecimal (as 0x...), and octal strings, e.g. in a loop, then oct would be useful.

When you know it's a hexadecimal string (e.g. /^0x/ && ...), I'd use the hex function. It makes your intent clear and obvious and, in my opinion, the code is far more readable.

The actual result is the same whichever you use:

$ perl -E 'say oct "0x47"; say hex "0x47"'
71
71
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And just a word of warning, /^0x/ may not do what you want:

$ perl -E 'say "0x47_not_hex" =~ /^0x/ ? "is hex" : "is NOT hex"'
is hex
$ perl -E 'say "0x47_not_hex" =~ /^0x[0-9a-fA-F]+$/ ? "is hex" : "is N
+OT hex"'
is NOT hex
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