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@BXor() (Read 1635 times)

Carl Underwood Senior Member Members Offline Posts: 1351 Location: New Hampshire Joined: Mar 11^th, 2003	@BXor() Feb 17^th, 2008 at 10:35pm	Print Post
	I don't know if I'm using the @BXor() function the wrong way or not, but I'm getting different results with it compared to when I run the same information through the built-in Windows calculator or do the binary math manually on paper. This code produces an answer of 1015765120, but the calculator and my manual calculations both produce 1234567890163840 Code var a as double var b as double var c as double a = 123456 b = 1234567890123456 c = @BXor(a, b) WriteLn(c) Code � Decimal � � � � � � � � � � � � � � �Binary � � � �� 123456 = � � � � � � � � � � � � � � � � � 11110001001000000 1234567890123456 = 100011000101101010100111100100010101011101011000000 ====================================================================== 1234567890163840 = 100011000101101010100111100100010110101100010000000

	Carl Underwood CDU Computer Consulting LLC Epsom, New Hampshire
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The Cow YaBB Administrator Offline Posts: 2530 Joined: Nov 22^nd, 2002	Re: @BXor() Reply #1 - Feb 17^th, 2008 at 10:46pm	Print Post
	An Exclusive Or function is rarely used on doubles. Try it on integers. Doubles are stored as 8 bytes with an exponent, mantissa, and sign, as opposed to the straight boolean encoding used for integers across 4 bytes. In the example you have above, it is clear that on the calculator you are using integers (by the number of bits used in the examples of the binary), but the SBasic is using doubles.

	Mark Lasersohn&&Programmer&&Lantica Software, LLC
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Carl Underwood Senior Member Members Offline Posts: 1351 Location: New Hampshire Joined: Mar 11^th, 2003	Re: @BXor() Reply #2 - Feb 17^th, 2008 at 11:12pm	Print Post
	Quote: Try it on integers. Same exact results with this: Code var a as int var b as int var c as int a = 123456 b = 1234567890123456 c = @BXor(a, b) WriteLn(c)

	Carl Underwood CDU Computer Consulting LLC Epsom, New Hampshire
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The Cow YaBB Administrator Offline Posts: 2530 Joined: Nov 22^nd, 2002	Re: @BXor() Reply #3 - Feb 17^th, 2008 at 11:22pm	Print Post
	Quote: Code b = 1234567890123456 The value 1234567890123456 overflows a 32 bit integer. A 32 bit signed integer ranges from approximately -2,000,000,000 to 2,000,000,000. An unsigned integer ranges from 0 to 4,000,000,000 - ish.

	Mark Lasersohn&&Programmer&&Lantica Software, LLC
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Carl Underwood Senior Member Members Offline Posts: 1351 Location: New Hampshire Joined: Mar 11^th, 2003	Re: @BXor() Reply #4 - Feb 17^th, 2008 at 11:47pm	Print Post
	Yeah, I just found out that smaller numbers are working. Unfortunately, I really wanted to run this on VERY large integers. Not a big deal - I can work around it. Thanks Mark.

	Carl Underwood CDU Computer Consulting LLC Epsom, New Hampshire
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Carl Underwood Senior Member Members Offline Posts: 1351 Location: New Hampshire Joined: Mar 11^th, 2003	Re: @BXor() Reply #5 - Feb 17^th, 2008 at 11:51pm	Print Post
	BTW... Just remembered, the reason I was using Doubles was because I knew Integers have a size limit, but then forgot about it when you suggested to use them.

	Carl Underwood CDU Computer Consulting LLC Epsom, New Hampshire
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The Cow YaBB Administrator Offline Posts: 2530 Joined: Nov 22^nd, 2002	Re: @BXor() Reply #6 - Feb 17^th, 2008 at 11:59pm	Print Post
	If I may ask, what are you up to? You may be able to manage to work with large entities by bit shifting each byte in the entity into one byte in an array of single bytes, and then xor-ing those bytes. This is a very simple and effective means of encryption (but you didn't hear that from me!)

	Mark Lasersohn&&Programmer&&Lantica Software, LLC
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Carl Underwood Senior Member Members Offline Posts: 1351 Location: New Hampshire Joined: Mar 11^th, 2003	Re: @BXor() Reply #7 - Feb 18^th, 2008 at 12:26am	Print Post
	Yeah, I was looking at encrypting some data. But, it may be easier to use TrueCrypt on the file itself.

	Carl Underwood CDU Computer Consulting LLC Epsom, New Hampshire
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The Cow YaBB Administrator Offline Posts: 2530 Joined: Nov 22^nd, 2002	Re: @BXor() Reply #8 - Feb 18^th, 2008 at 12:28am	Print Post
	If its an ASCII file, read it in and operate on it byte by byte (as a string).

	Mark Lasersohn&&Programmer&&Lantica Software, LLC
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