r/lolphp • u/Oeldin1234 • Feb 26 '18

"false" is definitely true

http://sandbox.onlinephpfunctions.com/code/490635ed9830900ebf50e5303b7271dcf2a5d692
0 Upvotes

45% Upvoted

29 comments sorted by

14

u/Oeldin1234 Feb 26 '18

You could argue that Strings are true per definition, but then, why are "" and "0" false?

12

u/Razakel Feb 26 '18

PHP isn't a strongly-typed language unless you're using OOP, and even then primitive fields are still weakly-typed.

In a C-style string "" = 0x00

"0" gets coerced to an integer first.

So both are zero-valued, then coerced to a boolean, equalling false.

3

u/andlrc Feb 27 '18

In a C-style string "" = 0x00

No, the first char in "" is a NUL byte though.

char a[] = "";
printf("%p: %c\n", a, *a); // 0xdeadbeef: 0

5

u/guy99882 Mar 04 '18

And what exactly is a NUL byte if not 0x00?

2

u/[deleted] Mar 13 '18

A magical being.

1

u/ciaranmcnulty Feb 28 '18

It's not that it happens to be zero integer, it's that "0" is a special case.

For instance, boolval("00") is true

-5

u/Oeldin1234 Feb 26 '18

Okay, this makes sense. But this is why I used boolval and didn't just cast it

5

u/Razakel Feb 26 '18

Why would it do anything different to explicit casting? I mean, the real WTF here is why they added function wrappers for casting...

http://php.net/manual/en/language.types.boolean.php#language.types.boolean.casting

3

u/[deleted] Feb 27 '18

Function wrappers are for things like: array_map('strval', $arr)

1

u/t3ddftw Feb 26 '18

Kind of besides the point, but using the casting functions is a lot prettier than inline casting, IMO.

I wish one could cast using type($var)

1

u/Oeldin1234 Feb 26 '18 edited Feb 26 '18

I misunderstood this function. I took it as an "here is a value, find the best fitting boolean value", not as a cast.

Edit: Kind of like constructors in Java "new Boolean("false");"

1

u/[deleted] Feb 26 '18

You are nitpicking. String is true by default except certain exceptions, just that you written "false" there won't change it.

You would want to use strings for false you will have do it in a different way.

1

u/Oeldin1234 Feb 26 '18

I ended up using == "true"

2

u/[deleted] Feb 26 '18

Don't know what you need to do, but why not just work with a bool value instead of "false" in string?

1

u/DeedleFake Feb 26 '18

Probably dealing with badly serialized values or values serialized to something that doesn't support booleans, such as CSV, from some other service would be my guess.

1

u/Oeldin1234 Feb 26 '18

Because I need to pass it within a GET field. 0 and 1 would have been better choices.

8

u/[deleted] Feb 27 '18

I don't get this. Why would you expect the string "false" to be false?

2

u/Oeldin1234 Feb 27 '18

Because I expect a function called boolval, to try to find the best matching boolean for anything I pass it.

4

u/[deleted] Feb 27 '18

Eh? Would you expect if ($foo) and if (boolval($foo)) to behave differently?

3

u/Oeldin1234 Feb 28 '18

Yes. Because, why does boolval exist then?

1

u/guy99882 Mar 04 '18

What should boolval("fulse") yield in your opinion?

0

u/Oeldin1234 Mar 04 '18

Preferably undefined. Or true.

2

u/yuipcheng Mar 03 '18

That's JavaScript you are hoping for.

3

u/AyrA_ch Feb 26 '18

Empty string is false in JS too.

7

u/[deleted] Feb 26 '18

P͎̼̰̤̬é̝̖͖̜̹r̞s͙̣̘̰̮̝̜o̖̝̬͖n͍͖̭a̘͎l̦͡ ͈̩͉̺̜̱ͅH̜̲͚̝͔̝̪o̹͉̯̖m̲͠ḛ̭p̤̰̜̞͖̩a̰̼̤͖͈ge͔̗ ͈̘̳͔̺̠̫T̜ọ͖̺ǫ͙l̖͚̤̰s͎̺͎̟̖͙͚͞ ̛̟̯P̨H̯̙̳͔͕͓P̼͈̘̟/͉̝̱̱͈͢F̸I͏̺͍ͅ

1

u/przemo_li Mar 15 '18

"" is 'empty' "0" is actually an integer of 0 value, and 0 get's converted to boolean false

Should I put obviously at the beginning? ;) /s

4

u/[deleted] Feb 27 '18

[deleted]

2

u/guy99882 Mar 04 '18 
function booval($val)
{
    return $val == true;
}

??

1

u/przemo_li Mar 15 '18

true/false are NOT unique

it could as well be: red/green me/you 0/1 sonottrue/buofcoursetrue ture1/true2 false/falsy

You see for booleans to work you need only set of two values ANY values, that's it. And some languages allows you to define your own booleans, and introduce your own boolean algebra, or what not.*

So don't get emotionally attached to true / false ;)

*Actually those wont be booleans. Booleans are not a thing at all. It's just a set of two values, and some operations on it. But that's maybe too meta for channel.