Editing 163: Donald Knuth

{{comic
| number    = 163
| date      = September 27, 2006
| title     = Donald Knuth
| image     = donald_knuth.png
| titletext = His books were kinda intimidating; rappelling down through his skylight seemed like the best option.
}}

==Explanation==
{{w|Donald Knuth}} is a computer science Professor Emeritus at {{w|Stanford University}} who is famous for writing ''{{w|The Art of Computer Programming}}'' and developing the <span class="texhtml"><span style="font-family:cmr10, LMRoman10-Regular, Times, serif;">T<span style="text-transform:uppercase; vertical-align:-0.5ex; margin-left:-0.1667em; margin-right:-0.125em;">e</span>X</span></span> computerized typesetting system.

In computer science, an array is a structure that stores multiple values in a fixed order, and the elements are accessed by their index number.  In {{w|Fortran}}, for instance, one writes <tt>array(1)</tt> to access the first element in the array. Most "modern" (read: descended from {{w|C (programming language)|C}}) languages use 0 as the index for the first element in the array, but it is possible (if one is careful about it) to ignore the 0th element and use 1 as the first index. In some programming languages, such as {{w|Pascal (programming language)|Pascal}} or {{w|Ada (programming language)|Ada}}, it is possible to select an arbitrary range of indices for each array type, so the first index might not only be 0 or 1, but also −42 or 100000. [[Cueball]] is complaining that [[Black Hat]] was not consistent in his choice of where to start his arrays. This is a valid complaint, as a lack of such consistency can make coding errors both more likely and more difficult to detect.

Black Hat cites Donald Knuth to support his rebuttal, but the quote he uses does not seem relevant. Presumably, Black Hat had illegally entered the professor's house in order to question him on indices. Donald Knuth's words were not an intellectual response to the question, but rather an alarmed response to the presence of an intruder. It is not clear if Black Hat is aware of this.

The title text suggests that Black Hat finds Knuth's books intimidating, due to perhaps their size or complexity, to the extent that he considers breaking into Knuth's house (a risky, difficult crime) to be the better option in finding his answer. Even for Donald Knuth's books, this is very exaggerated and illogical behavior.{{Citation needed}}

In ''[[xkcd: volume 0]]'', four other responses are included:
* "Should array indices start at 0 or 1? My compromise of 0.5 was rejected without, I thought, proper consideration." - {{w|Stan Kelly-Bootle}}
* "What are you doing with that thing? Eww, it's still alive!" - {{w|Paul Graham (programmer)|Paul Graham}}
* "I'm calling the police once I get my cell phone back from your squid." - {{w|Bruce Schneier}} 
* "Sorry, I thought you were Microsoft." - {{w|Richard Stallman|RMS}}

==Transcript==
:[Black Hat and Cueball are sitting back to back at two separate desks, typing.]
:Cueball: Man, you're being inconsistent with your array indices. Some are from one, some are from zero.
:Black Hat: Different tasks call for different conventions. To quote Stanford algorithm's expert Donald Knuth, "Who are you? How did you get in my house?"
:Cueball: Wait, what?
:Black Hat: Well, that's what he said when I asked him about it.

==Trivia==
Later, the topic of breaking into a software expert's house through the skylight became topic of [[225: Open Source]] again.

This is the first xkcd comic featuring [[Donald Knuth]].

{{comic discussion}}

[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Donald Knuth]]
[[Category:Programming]]
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