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The story of the $500,000,000 error.
In 1996, an unmanned Ariane 5 model rocket was launched by the European Space Agency.
Onboard was software written to analyze the horizontal velocity of the spacecraft. A conversion between a 64-bit floating point value and a 16-bit signed integer within this software ultimately caused an overflow error just forty seconds after launch, leading to a catastrophic failure of the spacecraft.
That day, $7 billion of development met it's match: a data type conversion.12 -
I hope devRant doesn't store ++ count as a signed 8-bit integer... Otherwise the next ++ this rant gets sets it to -128!
2 -
I have not researched it so I'm not sure if this is a widely known thing but I figured out a sort of hacky way to get a max integer value:
-Declare an unsigned int.
-Subtract 1
-Divide 2
That is your max signed int value
int main(){
unsigned int a = 0;
a--;
std::cout << a / 2 << std::endl;
}7 -
The tons of undefined behaviour in C that ought to have been implementation defined instead, and increasingly sadistic compiler writers on the other side.
Like signed integer overflow that should just do what the underlying machine does, i.e. in practice, wrap around two's complement.
But the wierdest UB is when a C source code line has a non-matching ' or ". WTF, this should have been a compile time error!2 -
Why do io-interfaces usually use a signed integer to return the number of bytes processed?
Like seriously, you literally can't write/read less than 0 bytes.4 -
A bit longer rant, somehow triggered by the end of this rant:
https://devrant.com/rants/7145365/...
The discussion revolved around strpos returning false or a positive integer.
Instead of an Option or a Exception.
I said I'm a sucker for exception, but I'm also a sucker for typing.
Which is something most languages lack - except the lower level ones like C / C++.
I always loved languages which have unsigned and signed types.
There, I said it... :) I know that signed / unsigned is controversial, Google immediately leads to blog entries screaming bloody murder because unsigned can overflow – or underflow, if someone tries to use a -1on an unsigned integer.
Note that my love is only meant for numeric types, unsigned / signed char is ... a whole can of insanity on its own.
https://phoronix.com/news/...
If you wanna know more.
Back to the strpos problem, now with my secret love exposed:
strpos works on a single string, where a string is a sequence of chars starting with 0.
0 is a positive integer.
In case the needle (char that should be looked up in the string) cannot be found in the haystack (the string), PHP returns "false".
This leads to the necessity of explicitly checking the type as "0" (beginning of string, a string position)... So strpos !== false.
PHP interprets 0 as false, any other integer value is true.
In the discussion, the suggestion came up to return -1 if a value could not be found – which some languages do, for example Scala.
Now I said I have a love for unsigned & signed integers vs. just signed integers...
Can you guess why the -1 bothers me very much?
Because it's a value that's illogical.
A search in a sequence that is indexed by 0 can only have 0 or more elements, not less than zero elements.
-1 refers to a position in the sequence that *cannot* exist.
Which is - of course - the reason -1 was chosen as a return value for false, but it still annoys me.
An unsigned integer with an exception would be my love as a return value, mostly because an unsigned integer represents the return value *best*. After all, the sequence can only return a value of 0 ... X.
*sigh*
Yes, I know I'm weird.
I'm also missing unsigned in Postgres, which was more or less not implemented because it's not in the SQL standard...
*sob*30 -
!rant
So I decided to collab with a website's maker (who i wont name here) to create something like r/place. (not an exact copy.)
I decided to start by learning their API, and customizing the server later.
I asked the guy for some help, and HOLY SHIT.
Let's start off by this: I had to request a chunk. The response data was in binary. 4 bits meant 1 pixel, so right away, I had to deal with that in my code.
No problem, just decided to use C# instead of JS. (see https://www.devrant.io/rants/547013)
I was finally done after a couple of mental breakdowns, and decided to implement updates.
I needed to use webhooks, and that was completely fine. But when I got "C1FFFF0000CA06" as response (in hex), I seeked some help.
C1 is the operation type: it means that a pixel was updated.
FFFF and 0000 were the chunk coordinates. But remeber: it's a signed integer. Guess what, I had to use Two's compliment. I decided to be a lazy asshole and only check for "00000000" because I was only displaying chunk 0,0.
CA06: This is a weird one. It's 2 bytes, and CA0 contains the X and Y coordinate of the pixel (in the chunk), and 6 contains the new color of the pixel.
I was sent the following code to work with 0xCA06:
color = 0xF & buffer
x = buffer >> 10
y = (buffer >> 4) & 0x3F
So I tried to do it, and it didn't work. I'm not blaming the developer of the server (original dev is reddit) because maybe I screwed up, but which guy will have a night of frustration and debugging?
Me.
P.S.: Dev, if you see this, I'm sorry. This API is way too complicated. I know we need to save bandwith and stuff, but damn.1
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