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0 pointsriverlong4y ago0 comments

Where in C is 0 truthy (or 1 falsy)?

0 comments

strcmp,memcmp,etc. return 0 for equality, maybe you'd count that? But it's not really indicating "true", more "no difference".

main() returns 0 for success, but I expect that is owed more to Unix.

A lot of (e.g. Linux) system calls return 0 for success and an error value on error, but again that's more down to Unix than C.

riverlongOP4y ago

I wouldn't count strcmp, etc. It returns < 0 if str1 is shorter and > 0 if str1 is longer. Returning 0 means there is 0 difference. That's not a True/False.

"0" is not a "truthy" exit code for a system call, it rather denotes the absence of an error.

In my view, a value X being "truthy" means that `bool(X)` evaluates to TRUE, or `if(X)` gets executed.

vegetablepotpie4y ago

I think it’s where many functions return 0 when they are successful.

leeoniya4y ago

maybe cause there's only one way to succeed and many ways to error. 0 success and 1..N are error codes.

what is a reasonable alternative?

(this isnt the same as 0 false and 1 true)

toomim4y ago

Ok, but:

     success vs. fail

is different than:

     true vs. false

They're both binary, but only one is boolean.

voxic114y ago

https://pubs.opengroup.org/onlinepubs/009695399/basedefs/std...

saagarjha4y ago

I think those go in the opposite direction.

foobiekr4y ago

Well, unix, as in exit codes.

riverlongOP4y ago

Yeah, exit codes aren't what I'm talking about here.

In Hoon/Nock, `if(0)` literally gets interpreted as True. That's insane.

tromp4y ago

In lambda calculus, true and false are conventionally represented as functions

    lambda x. lambda y. x

and

    lambda x. lambda y. y

so that "if b then x else y" is represented by "b x y". When identifying booleans with bits, it seems natural to write this as "bit x_0 x_1" rather than "bit x_1 x_0" where the arguments seem to be in the wrong order.

This is one possible justification for identifying true with 0 and false with 1.

knownjorbist4y ago

It's not insane, just dissimilar to what you're used to.

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pasquinelli4y ago

i don't really see why. if anything is insane, it's interpreting a number as true or false. but if you're doing that anyway, then you pick a number for false, or you pick a number for true. 0 is a natural number to pick for whichever truth value, because it's the base case of the natural numbers.

it's unconventional, but no more insane than 0 = false, which, again, _is_ insane, but conventional.

i'm not bothered either way

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jstanley4y ago

strcmp,memcmp,etc. return 0 for equality, maybe you'd count that? But it's not really indicating "true", more "no difference".

main() returns 0 for success, but I expect that is owed more to Unix.

A lot of (e.g. Linux) system calls return 0 for success and an error value on error, but again that's more down to Unix than C.

riverlongOP4y ago

I wouldn't count strcmp, etc. It returns < 0 if str1 is shorter and > 0 if str1 is longer. Returning 0 means there is 0 difference. That's not a True/False.

"0" is not a "truthy" exit code for a system call, it rather denotes the absence of an error.

In my view, a value X being "truthy" means that `bool(X)` evaluates to TRUE, or `if(X)` gets executed.

vegetablepotpie4y ago

I think it’s where many functions return 0 when they are successful.

leeoniya4y ago

maybe cause there's only one way to succeed and many ways to error. 0 success and 1..N are error codes.

what is a reasonable alternative?

(this isnt the same as 0 false and 1 true)

toomim4y ago

Ok, but: