Cody Boone Ferguson
3deb7ae603
Amongst the changes here is that we do not need to have the hex or html
code (numbers) for open and close parentheses (in links) as there are
names. '(' is & followed by lpar; and the ')' is the same but 'rpar;'
instead. This makes it easier to remember and type and it generates the
same html as well (they are all valid). Now the markdown files are
consistent in this (in some cases hex was used and in others the html
code).
Although many markdown files were updated no html files needed to be
updated as it generates the same html. Even so I ran the appropriate
rules to do so just to verify this.
158 lines
4.6 KiB
Markdown
158 lines
4.6 KiB
Markdown
## To build:
|
|
|
|
``` <!---sh-->
|
|
make all
|
|
```
|
|
|
|
There are two alternate versions, one that has an increased buffer size and one
|
|
that uses `fgets()`; neither are completely functional. See below section [Bugs
|
|
and (mis)features](#bugs-and-misfeatures) for details and the [Alternate
|
|
code](#alternate-code) section for how to use.
|
|
|
|
|
|
### Bugs and (Mis)features:
|
|
|
|
The current status of this entry is:
|
|
|
|
> **STATUS: uses gets() - change to fgets() if possible**
|
|
|
|
For more detailed information see [1994/schnitzi in bugs.html](../../bugs.html#1994_schnitzi).
|
|
|
|
|
|
## To use:
|
|
|
|
``` <!---sh-->
|
|
./schnitzi < textfile
|
|
```
|
|
|
|
|
|
## Try:
|
|
|
|
``` <!---sh-->
|
|
./try.sh
|
|
```
|
|
|
|
|
|
## Alternate code:
|
|
|
|
These alternate versions are for those who wish to help with getting the entry
|
|
to use `fgets(3)`. See the
|
|
FAQ on "[gets and fgets](../../faq.html#gets)"
|
|
for why this is desired.
|
|
|
|
The first version, `schnitzi.alt.c`, uses `fgets(3)` but when fed its own code
|
|
it will generate code that still uses `gets(3)`. What's more that code will not
|
|
compile. Other functionality of the alt version works fine.
|
|
|
|
The second version, `schnitzi.alt2.c`, has an increased buffer size but when fed
|
|
its own source code it will generate code that, although it can compile but, it
|
|
has the original buffer size. This is due to a comment which is explained in
|
|
more detail in [1994/schnitzi in bugs.html](../../bugs.html#1994_schnitzi).
|
|
|
|
|
|
### Alternate build:
|
|
|
|
``` <!---sh-->
|
|
make alt
|
|
```
|
|
|
|
|
|
### Alternate use:
|
|
|
|
Use `schnitzi.alt` and `schnitzi.alt2` as you would `schnitzi` above except that
|
|
feeding the source code to it will not work right.
|
|
|
|
|
|
### Alternate try:
|
|
|
|
``` <!---sh-->
|
|
./try.alt.sh
|
|
```
|
|
|
|
|
|
## Judges' remarks:
|
|
|
|
Try:
|
|
|
|
``` <!---sh-->
|
|
./schnitzi < schnitzi.c
|
|
```
|
|
|
|
Compare the output of the program with its source. Sure the output
|
|
is different, but there is more than meets the `diff`'s eye. Can you
|
|
find out why?
|
|
|
|
You might also wish to redirect the output to another file,
|
|
compile it and compare how it works to the original code.
|
|
|
|
|
|
### NOTICE to those who wish for a greater challenge:
|
|
|
|
**If you want a greater challenge, don't read any further**:
|
|
just try to understand the program via the source.
|
|
|
|
If you get stuck, come back and read below for additional hints and information.
|
|
|
|
|
|
## Author's remarks:
|
|
|
|
This is a program which takes any text file as input and 'flips'
|
|
the input file along a diagonal running from the top left corner
|
|
down to the bottom right. In other words, the first row in the
|
|
file ends up written down the first column of the result, the
|
|
second row is written down the second column, etc. The program
|
|
is run by redirecting a file into the executable on the command
|
|
line; for instance, for the file 'info', the program
|
|
would be run as follows:
|
|
|
|
``` <!---sh-->
|
|
./schnitzi < info
|
|
```
|
|
|
|
The program generates interesting results when its source file is
|
|
used as input:
|
|
|
|
``` <!---sh-->
|
|
./schnitzi < schnitzi.c
|
|
```
|
|
|
|
The result of this command is a program which does the exact same
|
|
thing -- in other words, both the program and the "flipped"
|
|
version of itself work identically (you'll need to redirect the
|
|
output of the above command into a separate file and compile it).
|
|
You might notice some differences in the flipped version, though.
|
|
First off, a secret message becomes visible that was not visible
|
|
in the original program. Also, much of the code shows up in
|
|
different places in the flipped program than it appeared in the
|
|
first program. My first version of this program was perfectly
|
|
symmetrical along the diagonal, but I later found out there were
|
|
interesting ways to break the symmetry. The best way to see this
|
|
is to load both the original and flipped versions of the program
|
|
into an editor and switch back and forth between them rapidly.
|
|
|
|
C tokens longer than a character (such as `main()`) proved difficult
|
|
to use in both the original and flipped versions (after flipping,
|
|
they show up as a string of single letters on successive lines).
|
|
However, I found that it was possible to get around this through
|
|
a few well-placed comments. An earlier version of this program
|
|
used nearly every single-character token in the "shared" area;
|
|
however, it proved to be too large for contest guidelines (although
|
|
the code itself is only about 300 characters, the extra whitespace
|
|
needed to pad it put it over the limit -- it nearly filled a 79 by
|
|
79 area, adding up to over 4000 total characters).
|
|
|
|
|
|
<!--
|
|
|
|
Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
|
|
|
|
You are free to share and adapt this file under the terms of this license:
|
|
|
|
Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
|
|
|
|
For more information, see:
|
|
|
|
https://creativecommons.org/licenses/by-sa/4.0/
|
|
|
|
-->
|