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if statement == false (i.imgflip.com)

submitted 1 week ago by tatterdemalion@programming.dev to c/science_memes@mander.xyz

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[-] raoul@lemmy.sdf.org 59 points 1 week ago

The boolean operator 'If and only if' do not have a relation with the program instruction 'if'.

The programatic 'if' is a jump, not a boolean operator. It do not have truth table.

In logic:, if and iff can be seen like functions taking two booleans and returning a boolean

'if a then b' (noted a -> b): return true if a is false or b is true. Example: 'if I eat pizza then I fart' This is true even if I fart all the time (if b is true, we do not care about the value of a) as long as I fart when eating pizza (if a is true, b must be also true)
'a <-> b' is equivalent to 'a -> b and b -> a': the two should be true at the same time. I can only fart will eating pizza and cannot fart otherwise.

[-] Hoimo@ani.social 5 points 1 week ago

So in programming, you'd write 'if' as:
not pizza or fart where the farting is irrelevant until the pizza is involved.

While 'iff' would be:
pizza equals fart where pizza means fart and no pizza means no fart.

I actually wrote iff as (not pizza and not fart) or (pizza and fart) before, and I'm pretty sure that's the way I wrote an iff in production code in the past, but your comment made me realize that "they should be true at the same time" can be tested really easily with equality.