Cody Boone Ferguson
1fad29cd2f
This includes some notices to those who wish for a greater challenge. In the 1998/schweikh3 the man page (and its copy to demonstrate the entry) have been updated slightly but only in comment (move 'or' from the command suggested to render it in text to its own line before the next command also in comment). The bugs file was updated for an entry or two.
143 lines
3.6 KiB
Markdown
143 lines
3.6 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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./dorssel
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# input some text
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echo text | ./dorssel
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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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How does the program decide which way to convert?
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What obsolescent feature are we talking about? (No, it's not a
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C language feature.)
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The author suggests that you try to answer the following questions:
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- Which character in the initializing string is totally irrelevant?
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- Which two relevant characters in the initializing string may be exchanged
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without altering the behavior?
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- Which characters in the initializing string are somewhat irrelevant, and to
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what values may they be changed without altering the behavior?
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- Which characters may be used to enlarge the initializing string by one without
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altering the behavior ?
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### Extra credit:
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Try doing what the last part of the last command in [try.sh](%%REPO_URL%%/1998/dorssel/try.sh) suggests.
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As in, do the following:
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``` <!---sh-->
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echo ". -..- . .-. -.-. .. ... .
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-.-. .... .- -. --. . - .... . .--. .-. --- --. .-. .- -- ... --- .. - -.. --- . ... -. --- - ... .... --- ..- -" | ./dorssel
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```
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and make the necessary adjustments.
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You might also want to read the [dorssel.html](dorssel.html) file.
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## Author's remarks:
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### Usage
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This program converts ASCII to [Morse
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code](https://en.wikipedia.org/wiki/Morse_code), and vice versa.
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The program reads in lines from standard input and writes its result to
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standard output. The direction of conversion is determined on a per
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line basis. Each line must consist of a maximum of 952 characters
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followed by a new line character and they must not contain any NUL
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characters. Otherwise, some characters may be lost in the conversion.
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- Encoding to Morse code: The program knows the Morse codes for all Latin
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letters (a-z, case insensitive) and decimal digits (0-9). Any other characters
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are replaced by an ASCII space, `' '`. Morse code per converted character is
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written as a sequence of `.` and `-` characters, each sequence followed by a
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space.
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- Decoding from Morse code: Morse code should be typed as sequences of `.` and
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`-` characters, separated by a space. Extra spaces will be echoed back (to
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separate words). Unknown sequences will be converted to a `?` character.
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### Notes
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The program assumes both source and execution character sets to be
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ASCII. As far as I can tell, the program is conforming and does not
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invoke undefined behavior.
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### Hints
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Try:
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``` <!---sh-->
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./dorssel < dorssel.c | ./dorssel
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```
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to see what variables, numbers, and functions are used. (Does a
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better job than most C beautifiers).
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- Filter your text twice (as in the previous sample) to obtain a version of your
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text that can be reversibly Morsified, i.e.
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``` <!---sh-->
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./dorssel < dorssel.c | ./dorssel | ./dorssel | ./dorssel
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```
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is the same as
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``` <!---sh-->
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./dorssel < dorssel.c | ./dorssel
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```
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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 without running the command below.
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If you get stuck, come back and read the below.
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The file [dorssel.html](dorssel.html) contains all the information needed to
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understand this program.
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For more information you might also try:
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``` <!---sh-->
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./dorssel < dorssel.md
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```
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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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