163: Donald Knuth
Title text: His books were kinda intimidating; rappelling down through his skylight seemed like the best option.
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 Fortran, for instance, one writes array(1) to access the first element in the array. Most "modern" (read: descended from 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 Pascal or 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.
- [Black Hat and Cueball are sitting back to back at two separate desks, typing. Black Hat has turned toward Cueball to respond to him.]
- Cueball: Man, you're being inconsistent with your array indices. Some are from one, some from zero.
- Black Hat: Different tasks call for different conventions. To quote Stanford algorithms expert Donald Knuth, "Who are you? How did you get in my house?"
- [Black Hat and Cueball are sitting back to back at two separate desks, typing. Cueball has turned toward Black Hat, confused.]
- Cueball: Wait, what?
- Black Hat: Well, that's what he said when I asked him about it.
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.
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