What is the correct color notation in XAML: #555 or #555555?

Question

Doing CSS throughout the last couple years, I eventually learned that the standard way to represent a gray color shade (or any color which repeated its first three characters) was to use only three characters instead of six, I assume for terseness:

• #555 instead of #555555
• #eee instead of #eeeeee

In XAML, however, I often see the opposite:

• #555555 instead of #555
• #eeeeee instead of #eee

Are there any situations in XAML when one will work and not the other, or one consumes more memory, etc., or is this just a long/short notation issue and has no practical ramifications?

Answer 1

In either CSS or XAML both forms (plus more) are valid..

Answer 2

Technically speaking I would say that the full six characters is more correct in any case as the abbreviated version is just expanded to a six. Two bytes per RGB.

I also prefer the 6 digit as I am then able to keep things consistent looking.

Answer 3

edit whoops, completely skipped over the XAML bit. The stuff below still relates to CSS though. Sorry mate

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According to the W3C, they've been the same since CSS1. I've not met a browser yet that'll display #abc any different to #aabbcc.

gray color shade (or any color which repeated its first three characters)

I may be misreading your question, but you can do more than just gray. The hext notations are #rgb, or #rrggbb. So, #123 = #112233, not #123123 :-)

Answer 4

Neither notation is truly more correct than the other. It's largely just a matter of preference.

The 3-digit format, or #rgb, is simply a short-hand format that expands to #rrggbb, giving you an option to leave out a few repeated characters.

#555 => #555555
#abc => #aabbcc

The exception is in specifics -- e.g., #e5a9bc can not be accurately described in or abbreviated to only 3 digits.

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I would guess the common preference for not using 3-digit notation in XAML is be based in the fact that not all markup languages support them -- HTML.