Re^4: Hex String XOR

in reply to Re^3: Hex String XOR
in thread Hex String XOR

tobyink,

Reading the Camel book (3rd and 4th editions), "...if both operands are strings...the operators do bitwise operations between corresponding bits from the two strings. In this case there's no arbitrary limit..."

So the following code should work (untested) and be faster than calling a subroutine and looping:


my $result = '112233112233112233112233112233112233112233112233112233' 
+^ 
    'aabbccaabbccaabbccaabbccaabbccaabbccaabbccaabbcc112233';
[download]

I used this technique to generate a 8-byte CRC for arbitrary text strings by using 'substr' to take 8-byte substrings. I needed the looping for that.

Regards...Ed

"Well done is better than well said." - Benjamin Franklin

Comment on Re^4: Hex String XOR Download Code

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Re^5: Hex String XOR by tobyink (Canon) on Mar 13, 2012 at 01:19 UTC
Yes, `^` does work on strings, but as the OP mentioned, it works on the string's bytes, not the hexadecimal numbers encoded in the string. `$ perl -E"say '112233'^'aabbcc'" PPPPPP $ perl -E"say sprintf '%x', 0x112233 ^ 0xaabbcc" bb99ff` [download] My code gives the latter behaviour (which the OP wants) on hexadecimal strings of arbitrary length. `perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'`	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^5: Hex String XOR
by tobyink (Canon) on Mar 13, 2012 at 01:19 UTC

Yes, ^ does work on strings, but as the OP mentioned, it works on the string's bytes, not the hexadecimal numbers encoded in the string.

$ perl -E"say '112233'^'aabbcc'"
PPPPPP

$ perl -E"say sprintf '%x', 0x112233 ^ 0xaabbcc"
bb99ff
[download]

My code gives the latter behaviour (which the OP wants) on hexadecimal strings of arbitrary length.

perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

[reply]
[d/l]
[select]

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