explain xkcd - User contributions [en]

Talk:1638: Backslashes

2016-02-03T06:31:40Z

141.101.66.83: /* I don't think the regex is invalid */ new section

It should be noted that this also occurs in almost every programming language where "\" is the escape character. i.e.
print("Hello")
> Hello
print("\"Hello\"")
> "Hello"
print("\\Hello\\")
> \Hello\
Oh, and by the way, isn't this the third comic to mention "Ba'al, the Soul Eater"? Maybe we should start a category. (Others are [http://www.explainxkcd.com/wiki/index.php/1246:_Pale_Blue_Dot 1246] (title text) and [http://www.explainxkcd.com/wiki/index.php/1419:_On_the_Phone 1419].)
[[Special:Contributions/173.245.54.29|173.245.54.29]] 06:14, 3 February 2016 (UTC)

== I don't think the regex is invalid ==

According to <tt>man grep</tt> you need to specify the <tt>-E</tt> option to use extended regex; without it unescaped parentheses are not interpreted, so they don't need to match.

My - very wild - guess is that it was the command he used to find the line with the most special characters, but I am not confident enough to edit the article (if someone can confirm?).

342: 1337: Part 2

2016-01-20T18:34:13Z

141.101.66.83: /* Explanation */ link edition

{{comic
| number = 342
| date = November 13, 2007
| title = 1337: Part 2
| image = 1337 part 2.png
| titletext = Trivia: Elaine is actually her middle name.
}}

==Explanation==
"Like a ring in a bell" appears to be a reference to the {{w|Chuck Berry}} song {{w|Johnny B. Goode}}, in which Berry describes a young boy (like himself) who becomes a guitar-playing prodigy. Apparently, Elaine learned to program as quickly, easily, and skillfully as Johnny (and Chuck) learned to play rock 'n' roll.
{{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 TeX computerized typesetting system. He may not have a mountain hideaway {{Citation needed}} (a reference to ''{{w|Kill Bill}}'', by the way), but he would be one of the best mentors a budding hacker could have.

The {{w|A* search algorithm}} and {{w|Dijkstra's algorithm}} are {{w|Graph traversal|graph search}} {{w|algorithm}}s. And what study of algorithms would be complete without a healthy study about finding complexities? {{w|Computational complexity theory|Time complexity}} is the amount of time an algorithm takes to execute. Upper and lower bounds for complexity is written in {{w|Big O notation}}. Best possible execution of an algorithm is constant time, or O(1), said in words, for any given data set no matter how large the algorithm will always return the answer in the same time. However, constant time is extremely difficult to achieve; linear time (O(n)) is also very good. For more complex algorithms, [http://www.wolframalpha.com/input/?i=plot+x*log%28x%29 O( n*log(n) )] is good, but [http://www.wolframalpha.com/input/?i=plot+x*log%28log%28x%29%29 O( n*log(log(n)) )] is better. (Note that logarithms in different bases are proportional to each other. So this would hold true for any base >1.)

From the evidence that [[Mrs. Roberts]] has two children, a daughter named [[Elaine Roberts|Elaine]], and a younger son named Bobby (presumably [[Little Bobby Tables|Robert'); DROP TABLE students;--]]), we can assume that she is the same mother from [[327: Exploits of a Mom]]. Of course, the title text here explains that Elaine is only her middle name. In [[327]] we learned her first name is "Help I'm trapped in a driver's license factory". Mrs. Roberts appears to have had fun naming her children.

All comics in "[[:Category:1337|1337]]" series:
*[[341: 1337: Part 1]]
*342: 1337: Part 2 (this one)
*[[343: 1337: Part 3]]
*[[344: 1337: Part 4]]
*[[345: 1337: Part 5]]

This series was released on 5 consecutive days (Monday-Friday) and not over the usual Monday/Wednesday/Friday schedule.

==Transcript==
:[Cueball standing near a friend, who is on the floor near the armchair.]
:Friend: So the greatest hacker of our era is a cookie-baking mom?
:Cueball: Second-greatest.
:Friend: Oh?

:[A young Elaine with a ponytail is laying on the floor looking at the screen of a computer that appears to have been pieced together. A younger Bobby is finger painting at an easel.]
:Mrs. Roberts had two children. Her son, Bobby, was never much for computers, but her daughter Elaine took to them like a ring in the bell.

:[The back of a car is in frame. Mrs. Roberts is waving goodbye to her daughter who is wearing a backpack and is holding a walking stick. She is about to begin climbing a staircase built into a mountain.]
:When Elaine turned 11, her mother sent her to train under Donald Knuth in his mountain hideaway.

:[Donald Knuth is standing with a pointing stick at a chalk board with graph traversal patterns on it.]
:For four years she studied algorithms.
:Knuth: Child—

:[Knuth whips around slashing the stick like a sword. Elaine jumps and lands on the stick.]
:Knuth: Why is A* search wrong in this situation?
:''swish''
:Elaine: Memory usage!
:Knuth: What would you use?
:Elaine: Dijkstra's algorithm!

:[They are outside both working on a chalkboard with a separator down the middle so they cannot look at each other's work. Elaine is no longer wearing her hair in a ponytail.]
:Until one day she bested her master
:Knuth: So our lower bound here is O(n log n)
:Elaine: Nope. Got it in O(n log (log n))
:And left.

==Trivia==
*In this [http://www.youtube.com/watch?v=zJOS0sV2a24#t=21m30s Google-speech] Donald Knuth personally asked [[Randall]] what his ''n*log(log(n))'' algorithm for searching was, and Randall referred him to Elaine.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Elaine Roberts]]
[[Category:Comics featuring Mrs. Roberts]]
[[Category:Comics featuring Little Bobby Tables]]
[[Category:Comics featuring Donald Knuth]]
[[Category:1337|02]]

293: RTFM

2016-01-18T18:03:44Z

141.101.66.83: /* Explanation */ english language; a “fact” needs references

{{comic
| number = 293
| date = July 23, 2007
| title = RTFM
| image = rtfm.png
| titletext = Life is too short for man pages, and occasionally much too short without them.
}}

==Explanation==
The title RTFM is an acronym for "{{w|RTFM|read the f**king manual}}", which frustrated software manufacturers tell users when confronted with a simple question (most likely answered in the manual).

However, [[Cueball]] encounters a similar situation with a {{w|911}} call, in which the first question the 911 dispatcher asks is if Cueball has read the toaster's {{w|man page}} (man pages are the 'manual' for unix systems, but only describe commands and library functions, not hardware). Even if a man page existed, it is unreasonable to require the user of a toaster to read the manual just to avoid being stabbed in the face. The 911 dispatcher decides that as he has not read the man page, Cueball is not entitled to medical assistance, and hangs up.
The title text refers to the popular phrase "Life's too short", which asserts that because we only have a fixed amount of time on Earth, and that time can pass by quickly, we should make the most of it. That could mean, for example, don't spend time reading the documentation unless you actually experience a problem. The second part suggests that some people actually die because they didn't RTFM!

==Transcript==
:[Cueball with a knife sticking out of his heavily bleeding face stands in front of a toaster, which has an arm extending from the top of it. He is holding a telephone to his ear.]
:Cueball: Hello, 911? I just tried to toast some bread, and the toaster grew an arm and stabbed me in the face!
:911: Did you read the toaster's man page first?
:Cueball: Well, no, but all I wanted was--
:911: ''click''

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics with color]]