Big Willy's New Writeups

Why does taking a programming class in a language you already know suck so much? (thing)

2001-02-19T22:40:47Z

Why does taking a programming class in a language you already know suck so much? Allow me to explain with a short narrative:

Mr. X begins to lecture about variables and constants, a hopelessly minute and thoroughly understood topic for an individual such as myself who already codes in the language he is teaching. As I begin to snooze through his soporism, I miss his discussion about the differences between constants and variables, assignment to variables, the various types of variables, etc. Not a problem. I know this, after all.

Some time later, I am awakened and we promptly turn to our computers to begin work on the exercises that Mr. X has assigned for the day. No problem: "Write a program that demonstrates the difference between a constant and a variable." I write out the code in about 3 seconds. Next task: "Write a program that accepts a radius as input, stores it in a variable, and computes the circumference of the circle". Easy. Done in 3.2 seconds.
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vi (thing)

2001-02-19T04:07:43Z

This has always been a valuable little vi reminder list. I would hate to lose it.

Handy "vi" Guide 

CURSOR POSITIONING 

Ctrl-F  go forward a page
Ctrl-B  go backward a page
Ctrl-U  go up half a page
Ctrl-D  go down half a page
j       go down one line (faster than Cursor-Down)
k       go up one line (faster than Cursor-Up)
H       go to the top of the screen
M       go to the middle of the screen
L       go to the bottom of the screen
G       go to the bottom of the document
1G      go to the top of the document
nnnG    go to line number 'nnn' of the document
          Note: most positioning and modification commands can be  
          repeated 'nnn' times by using a repetition prefix; use 
          ESC to abort entering the prefix)
w       go forward one word
b       go backward one word
0       go to the first column of the current line
$       go to the last column of the current line
^       go to the first non-whitespace character on

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Guido Ubaldus' proof of the existence of God (idea)

2001-02-18T17:12:05Z

The problem is this:

Ubaldus made an algebraic mistake.

In lines 2 and 3, he included 3 +1's and 3 -1's. All's fine and well and everything equals zero. In line 4, there are 4 +1's and 3 -1's.

You can't add a term to one side without adding it to another

In essence, Ubaldus added 1 to the right side without completing the same operation on the left He may have been dealing with infinite series, but zero is zero anyway you slice it, even if you're talking about a billion terms of (1-1). The number of terms does not affect the outcome of the operation, until a person erroneously adds a 1 without adding a -1. Of course this will make falsely suggest 0 = 1. Had this worked out, I am not sure it proves there is a God anyway..

japh (thing)

2001-02-14T23:31:29Z

From Programming Perl, p. 992:

"Just Another Perl Hacker," a clever but cryptic bit of Perl code that when executed, evaluates to that string. Often used to illustrate a particular Perl feature, and something of an ongoing Obfuscated Perl Contest seen in Usenix signatures.

If that be the case, I prefer something more confusing, but by no means the hit of perl obfuscation:

#!/usr/bin/perl -w
$_="a<j3 8]}9[ 1~2+ -62` 4,+,.j?23h`}|{qj46] #+.*,)";$h=H8;
y|!&#'%;@*().,$"^:\|{}[]+_\-?<~` a-z0-9|a0c6e8b12345d7f9|d;
$_=pack($h,$_);tr#U-ZA-T\#7^?2g(&p:#J-ZA-I#;$_.="\n";print;

encryption algorithm (thing)

2001-02-07T22:05:24Z

DO NOT BE FOOLED. THIS IS NOT SECURE

Anyone who knows more than 2 things about cryptography knows that XOR encryption is insecure. The fact is that it's a polyalphabetic cipher except that the alphabet consists of 0 and 1 instead of A to Z. Allow me to quote Applied Cryptography by Bruce Schneier:

"The simple-XOR algorithm is really an embarassment; it's nothing more than a Vigenere polyalphabetic cipher...There's no real security here. This kind of encryption is trivial to break, even without computers...An XOR might keep your kid sister from reading your files, but it won't stop a cryptanalyst for more than a few minutes."

When wonko says "fairly secure encryption algorithm," he's only right if you consider fairly secure to be fairly secure from a crypto idiot. Sorry to be so harsh, but this was just oh so very ignorant. Putting faith in this kind of encryption has been the downfall of many "secure" products.

I will note…

C backslash codes (thing)

2001-02-07T01:35:15Z

Useful in your C strings...

Code    Meaning

\b      backspace
\f      form feed
\n      newline
\r      carriage return
\t      horizontal tab
\"      double quote
\'      single quote
\0      null
\\      backslash
\v      vertical tab
\a      bell
\N      octal constant where N is an octal constant
\xN      hexadecimal constant where N is a hexidecimal constant

This information is taken from Teach Yourself C, 2nd ed. by Herbert Schildt