where does 0x come from?

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Why are Hexadecimal Prefixed as 0x?

I just saw a comment a friend of mine made:

3x12=36
2x12=24
1x12=12
0x12=18

Which made me wonder..
Why did they choose 0x as prefix for hexadecimal numbers? Is there any history behind this decision?

you mean what is the history of 0x as a prefix vor hex-numbers? — Hinek, Nov 23 '10 at 15:30
@Hinek: exactly. why `0x` and not `0?` or `_` or any other character.. — default, Nov 23 '10 at 15:31
different languages systems actually have [a lot of ways](http://en.wikipedia.org/wiki/Hexadecimal#Representing_hexadecimal) to represent hexadecimal, both prefix and suffix, using `0`, `h` and even `$` and `\\`. — Andrzej Doyle, Nov 23 '10 at 15:33
In C you can type in numbers in three formats: A: decimal -> starting with 1 to 9 B: octal starting with 0 (like 037) C: hexadecimal starting with 0x One only needed some seperation — Traummaennlein, May 15 '17 at 12:16

score 5 · Accepted Answer · answered Nov 23 '10 at 15:32

5

I think, because x comes from hex and 0 is to indicate that it is a number.

answered Nov 23 '10 at 15:32

khachik

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So it would be possible to have something like `ax` to describe characters? Never heard of. :) This answer seems most reasonable though, thanks – default Nov 23 '10 at 15:44
@Default: No, but you could have `0xa`. – FrustratedWithFormsDesigner Nov 23 '10 at 16:12
`0xa` would still be a number. I merely suggested that, if it was to indicate a number (to use 0) could you then use a character (for instance a) to indicate a [hexadecimal] character? – default Nov 23 '10 at 16:32
@Default: If you wrote a compiler that accepted it, sure you could. That's really a decision that goes to the language designer. – FrustratedWithFormsDesigner Nov 23 '10 at 18:44
@Default It would be complicated if `axac` is a hex number, and `axag` a variable name, so language designers mostly choose `0x` as a hex. – khachik Nov 23 '10 at 20:25

FrustratedWithFormsDesigner · Answer 2 · 2010-11-23T16:13:08.053

1

0x means the number is probably hexadecimal. This applies in C/C++, and probalby other languages.

His comment is a joke. he starts with multiplication tables for the number 12, but when he gets to 0 he implies that 0x is not "0 multiplied by...", but instead is "hexadecimal" so 12 in hex is 18 in decimal.

edited Nov 23 '10 at 16:13

answered Nov 23 '10 at 15:30

FrustratedWithFormsDesigner

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score 0 · Answer 3 · answered Nov 23 '10 at 15:31

0

It's a joke on HEX numbers from WIKIPEDIA.

The first three are interpreted as multiplication, but in the last, "0x" signals Hexadecimal interpretation of 12, which is 18.

answered Nov 23 '10 at 15:31

Pablo Santa Cruz

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score 0 · Answer 4 · answered Nov 23 '10 at 15:36

0

'0x' means that the number that follows is in hexadecimal. It's a way of unambiguously stating that a number is in hex, and is a notation recognised by C compilers and some assemblers

answered Nov 23 '10 at 15:36

J Benjamin

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where does 0x come from?

4 Answers4

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