Landon Curt Noll
ed866b45e8
We move `tmp/format-headers.sh` into `bin/format-headers.sh`. We also add a few missing empty lines to `README.md`. We add `bin/format-headers.sh` to the `bin/README.md`. We run `bin/format-headers.sh` to perform the above. Performed `make www` to accomplish the above and to test under macOS.
118 lines
2.8 KiB
Markdown
118 lines
2.8 KiB
Markdown
## To build:
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``` <!---sh-->
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make
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```
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### Bugs and (Mis)features:
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The current status of this entry is:
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> **STATUS: INABIAF - please DO NOT fix**
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For more detailed information see [2001/cheong in bugs.html](../../bugs.html#2001_cheong).
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## To use:
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``` <!---sh-->
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./cheong digits
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```
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## Try:
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``` <!---sh-->
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./try.sh
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```
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## Judges' remarks:
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Be sure to give an even number of digits in the argument. Add a
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leading 0 if needed.
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The source code is nice, compact, and self documenting
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as all good programs should be! :-)
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## Author's remarks:
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### Operation
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Compile normally and run with one argument, an integer with 2n digits.
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Program will return the integer part of its square root (n-digits).
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For example,
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``` <!---sh-->
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$ cc -o cheong cheong.c
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$ ./cheong 1234567890
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35136
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$ ./cheong 0200000000000000000000000000
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14142135623730
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```
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Deviation from these instructions will cause undefined results. :-)
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### Portability
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This program runs normally on any ANSI C compiler and is ASCII dependent.
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Strict compiling gives just one unavoidable warning:
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``` <!---sh-->
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gcc -ansi -Wall cheong.c
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cheong.c:3: warning: third argument of `main' should probably be `char **'
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```
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### Obfuscation
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The main obfuscation is the algorithm used to calculate square roots,
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sometimes known as the longhand method. The basic algorithm is itself
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obfuscated in that it only uses subtraction to calculate square roots.
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For a detailed explanation, check Google or see Jack Crenshaw's article
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at
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<https://web.archive.org/web/20011215124349/http://www.embedded.com/98/9802fe2.htm>.
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This program uses an even more obscured version which includes the following:
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- A single string is used to store two numbers of different lengths
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- Operations are done in a weird hybrid of base 10 and base 20
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- Subtraction is done addition style, i.e. `4 - 8` equals `6` carry a `-1`
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- Recursive calls to `main()`
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#### Minor obfuscations:
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- Self documenting whitespace in rectangular code block, for fun and glory (view
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with fixed-width font)
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- Integer constants adjusted to less meaningful values, just for added confusion
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- Hard-to-read, meaningless variable names to spite the reader
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#### Challenges for the masses:
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- What are the meanings [sic, plural] of the variable `o`?
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- Why is `(c+999)%10-(D[I]+92)%10` not equivalent to `(c-D[I]+7)%10`?
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- How does the program terminate?
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- Is the programmer sane? ;-)
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### Appreciation
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Thanks goes out to Bobby Rohde for numerous suggestions on how to shorten
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the program.
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<!--
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Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
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You are free to share and adapt this file under the terms of this license:
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Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
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For more information, see:
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https://creativecommons.org/licenses/by-sa/4.0/
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-->
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