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Search - "0 indexed"
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PHP arrays.
The built-in array is also an hashmap. Actually, it's always a hashmap, but you can append to it without specifying indexes and PHP will use consecutive integers. Its performance characteristics? Who knows. Oh, and only strings, ints and null are valid keys.
What's the iteration order for arrays if you use them as hashmaps (string keys)? Well, they have their internal order. So it's actually an ordered hashmap that's being called an array. And you can produce an array which has only integer keys starting with 0, but with non-sequential internal (iteration) order.
This array weirdness has some non-trivial implications. `json_encode` (serializes argument to JSON) assumes an array corresponds to a JSON array if its keys are consecutive integers in increasing order starting with 0, otherwise the array becomes a JSON object. `array_filter` (filters arrays/hashmaps using callback predicate) preserves keys, so it will punch holes in the int key sequence if non-last items are removed, thus turning arrays into hashmaps and changing your JSON structure if you forget to discard keys before serialization.
You may wonder how JSON deserialization works, then? There's a special class for deserialized JSON objects, `stdClass`. It's basically a hashmap too, but it's an object, not an array, and all functions that would normally accept arrays won't work with it. So basically its only use is JSON (de)serialization. You can even cast arrays to objects, producing `stdClass`.
Bonus PHP trivia:
Many functions return nonsensical values. `preg_match`, the regex matching function, returns 1 for success, 0 for no matches and false for malformed regular expression. PHP supports exceptions, so it could just throw one on errors. It would even make more sense to return true, false and null for these three cases. But no, 1, 0 and false. And actual matches are returned by output arg.
`array_walk_recursive`, a function supposed to recursively apply callback to each element of an array. That's what docs say. It actually applies it to leafs only. It will also silently accept object instead of array and "walk" it, but without recursing into deeper objects.
Runtime type enforcing is supported for function arguments and returned values. You can use scalar types, classes, array, null and a few special keywords. There's also a `mixed` keyword, which is used in docs and means "anything". It's syntactically valid, the parser will accept it, but it matches no values in runtime. Calling such function will always cause a runtime error.
Strings can be indexed with negative integers. Arrays can't.
ReflectionClass::newInstanceWithoutConstructor: "Creates a new class instance without invoking the constructor". This one needs no commentary.
`array_map` is pretty self-explanatory if you call it with a callback and an array. Or if you provide more arrays of equal length via varargs, callback will be called with more arguments, one from each array. Makes sense so far. Now, you can also call `array_map` with null instead of callback. In that case it treats provided arrays as rows of a matrix and returns that matrix, transposed.5 -
Naaarf
Refactoring the whole day.
Someone who prefers while(list(...) = each(...)) or for($x=0; $x < count($array); $x++) wrote the following code, too.
if ($indexed == null || $indexed == "0" && $row[$x]["indexed"] == 0 || $indexed == "1" && $row[$x]["indexed"] == 1) ....
It's buggy. Why does this not surprise me?
This stuff. Whole day.
My brain feels foggy.5 -
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 -
Have to learn the Matlab language for school. It's proprietary, you have to pay for it, and arrays are not even 0 indexed!3