Cody Boone Ferguson
41abeda97a
In the line in README.md and index.html files that said:
### NOTICE to those who wish for a greater challenge
I added a ':' at the end of the line.
There were some entries that had a link fix in the index.html file but I
only looked up through 1995/leo as those still have to have a 'look and
feel' check and it would just slow things down.
89 lines
2.1 KiB
Markdown
89 lines
2.1 KiB
Markdown
## To build:
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``` <!---sh-->
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make all
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```
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## To use:
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``` <!---sh-->
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echo foo bar | ./dg
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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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Some C preprocessors got confused about single quotes in certain cases.
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In particular, the following source line:
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``` <!---c-->
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b12(ase(bco(acp(bi(acp(bcp(acp(bpl(aqu(bqu(A))))))))))))))))))))))))))))))
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```
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sometimes has to be changed to:
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``` <!---c-->
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b12(ase(bco(acp(bi(acp(bcp(acp(bpl('A'))))))))))))))))))))))))))))
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```
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particularly if the C preprocessor botches single quotes in cpp expansions,
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which we have done for the wider audience.
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## Author's remarks:
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If my preprocessor could hack it, I could write this as one single line rather
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than 4, but when I do that I get a complaint "defines nested too deeply".
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### NOTICE to those who wish for a greater challenge:
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**If you want a greater challenge, don't read any further**:
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just try to understand the program via the source.
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If you get stuck, come back and read below for additional hints and information.
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### How this entry works:
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This is another rot13 job (believe it or not) - the `#define`s are a
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novel way of adding tokens: `#define b12(x) 12 x` means that at
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some point in the source a `12` is followed by the compressed nested
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`#define`s. The `b12` gets the previous compression as an argument, and
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prepends the `12`, thus making another step in the recreation of the
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source. The `axx()` `#define`s do the same, but add tokens after.
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As for the rot13 algorithm, it relies on `index(3)` to find if the
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character is in the set `A-Za-z`. `l[]` is an array that gets filled
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with:
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``` <!---c-->
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"nopqrstuvwxyzzzzabcdefghijklmmmmNOPQRSTUVWXYZZZZABCDEFGHIJKLMMMM"
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```
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If `index(3)` says the char is in the alphabet, then XOR the offset
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with `16` to translate, and output, otherwise pass it unchanged.
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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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