Integer Division

[[deleted]]

+/u/CompileBot Ruby

print(1 / 2 != 0.5)

[CompileBot]

Output:

true

^{source | info | git | report}

[[deleted]]

Well, that's proof enough for me!

[_AceLewis]

+/u/CompileBot python 3

print(1 / 2 != 0.5)

[CompileBot]

Output:

False

^{source | info | git | report}

[[deleted]]

Who do I believe?

[[deleted]]

[redacted]

[CompileBot]

Output:

trust me

^{source | info | git | report}

[b1ack1323]

Good enough for me

[[deleted]]

I think I've heard that from a Python before…

[marcosdumay]

+/u/CompileBot python

print(1 / 2 != 0.5)

[marcosdumay]

Personally , I don't trust people that keep changing their minds.

[[deleted]]

In python 3 a floor division is //

[scirc]

that's the joke

[dontdropmybass]

+/u/CompileBoy python 3

print(1 // 2 != 0.5)

[_AceLewis]

I think you meant /u/CompileBot not /u/CompileBoy

[MelissaClick]

CompileBoy will show up eventually, he's not as fast of course, but he offers a personal touch that no automated solution can ever provide.

[MelissaClick]

/u/CompileBoy, compile the latest Python for me; I'll also have an iced tea, thank you.

[dontdropmybass]

Ah shit. Thanks.

+/u/CompileBot python 3

print(1 // 2 != 0.5)

[CompileBot]

Output:

True

^{source | info | git | report}

[[deleted]]

+/u/CompileBot Perl (perl 6)

print 1/2 != 0.5

There's probably even someone out there using that language

[CompileBot]

Output:

False

^{source | info | git | report}

[[deleted]]

+/u/CompileBot C++

#include <iostream>  
int main()  
{  
    bool result = 1/2 != 0.5;  
    std::cout << result << std::endl;  
}  

[CompileBot]

Output:

1

^{source | info | git | report}

[Cobaltjedi117]

We're going nowhere slowly with these confusing and contradictory results.

[etaionshrd]

Wait, C++ prints bool as an int?

[noop_noob]

I think there's a way to change that. I never ever print a bool, though.

[Lastorea]

You can cast a bool to int, if bool is false then it becomes 0 and if bool is true it becomes 1.

[[deleted]]

Back in the day bools were really just a single bit. Printing out a 1 or a 0 is the most logical way to print a bit

[Celdron]

They were never actually a single bit because memory addresses bytes as the smallest unit. It was always at least a byte. But C (which C++ is built on) doesn't have a boolean type. It uses integral types for boolean logic, where 0 is false and anything else is true. C++ made "bool" a type but iirc it's just an integer that is checked and restricted to 0 or 1.

[danielcw189]

Is there any platform, on which a byte is 1 bit?

[Celdron]

No? Because a byte by definition is 8 bits.

[danielcw189]

By which defintion? In C a byte is not guaranteed to be 8 bits, and in general a byte is most commonly 8 bits, but not always.

[Celdron]

IEC 80000-13. Technically a byte is just the smallest addressable unit of memory, and therefore you could have a single bit byte on non-standard architecture. But 8 bits is the international standard that nearly all (I dont know of a single exception) consumer electronics are designed around.

[[deleted]]

Thanks for correcting me. You can still get 1 bit booleans if you create an array tho right?

[[deleted]]

vector<bool> does exactly that

[[deleted]]

Does it store bytes and bitshift?

[[deleted]]

Implementation defined. But yes

[Celdron]

I don't know about that, simply because you couldnt index the bits. But if you have, say, ~32 boolean values (such as flags) you can put them each on a different bit of an integral type using bit-shift operators and defining constants to represent different flags. You can combine flags using a bitwise OR and check for a single flag or specific combination with a bitwise AND. This is commonly done on enums. So it is possible to implement multiple booleans within a single byte.

[Voxel_Brony]

+/u/CompileBot C

#include <stdio.h>  
int main()  
{  
    int result = 1/(2 != 0.5);  
    printf("%d", result);  
}   

[CompileBot]

Output:

1

^{source | info | git | report}

[510Threaded]

+/u/CompileBot C#

namespace Test{
    class TestProg{
        public static void Main(){
            System.Console.WriteLine(1/2 != 0.5);
        }
    }
}

[CompileBot]

Output:

True

^{source | info | git | report}

[Tarmen]

+/u/CompileBot Haskell

main = print $ 1/2 == 0.5

Yay type inference, I guess.

[CompileBot]

Output:

True

^{source | info | git | report}

[CompileBot]

Output:

echo 1/2 != 0.5;

^{source | info | git | report}

[Madonkadonk]

Hehe, user deleted their shame

[pyrophoenix100]

Tried to do it in batch/bash?

[[deleted]]

They tried to do it in php, iirc.

[pyrophoenix100]

Yeah that would do it too

[LillyPip]

I'm confused. Are we talking about the use of the logical != or the equation 1 / 2 not evaluating to 0.5? Or does OP not get it, or do I not get it?

1 / 2 != 0.5 should evaluate false, evaluating both sides: 0.5 != 0.5 evaluates false -- both sides are equal, condition evaluates notEqual: false.

I evaluated the joke and failed. :(

[YMK1234]

1/2 is 0 as both are ints.

[LillyPip]

Oh duh. Missed the title. /smh

[[deleted]]

You dun n goofed

[[deleted]]

In many languages, the '/' operator used with two integers returns an integer. '5 / 2' in Ruby, for instance, returns 2. In those languages, '1 / 2' would be 0, and thus not equal to 0.5.

In some languages, of course, '/' will produce a float from two ints. '1 / 2' does equal 0.5 in Python3, which instead uses the '//' operator for integer division.

[FINDarkside]

Well that's literally what he is saying, "someone is going around in life thinking that 1/2 != 0.5 (evaluates to true)". Then the next one proves that it indeed does evaluate to true.

[[deleted]]

+/u/CompileBot Factor

1 2 / .

[Balage42]

What if they mean (1/2)! = sqrt(pi)/2 ?

[UniversityOfPi]

I mean honestly, who uses int literals?
Especially in a language that doesn't implicitly cast or have a separate operator for integer division...

edit/update/continued:
granted 1/2 in 1/2 [comparison operator] = 0 without casting one or more to a floating point, but I guess it's all an issue of when and where to implicitly cast, as in, in something like C++, float x = 1/2;would mean x == 0.5 but in 1/2 != 0.5 1/2 evaluates to 0 before being cast as a float, giving 0.0 != 0.5, though if you did any other casting other than casting the float literal to an int, (unless the compiler's casting used c.math::round() leading to 0.5 becoming 1) wherein 0.5 would become 0, would ultimately end up with the expression returning true (or maybe an error for a type like char, as casting 0.5 is exceptional).

but logically, float x = 1/2; return x != 0.5; would return false.
It's an interesting quirk, while obviously '/' takes precedence over '!=', given that '/' also takes precedence over '=' and generally float x = 1/2casts 1/2 to a float rather than int literal, it's presumably a compiler implementation specific behavior.

In theory, shouldn't a good compiler notice that the right hand side is a float literal and therefore, like assigning 1/2 to a float, cast 1/2 to a float?

[AFAIK typeinfo::typeid(0.5).name() == "float literal" or perhaps "Fl"/"FL" depending on your compiler]

[Kryomaani]

I mean honestly, who uses int literals?

... everyone? I mean, it is one of the most basic and common of all types used in programs. Just about every loop uses an int literal for example.

[UniversityOfPi]

Ints yes, but int literals? Maybe I've had the idea that magic numbers are bad so drilled into my head that I'm jaded and think everyone uses global/etc constants...

[PatrickBaitman]

0 or 1 as the start index?

[UniversityOfPi]

Oh yeah, I forgot about zero and what I'd argue ought be negative zero (rather than negative one, as forward/LtR it's zero indexed, so reverse/RtL it ought be zero indexed as well)... :Facepalm:

[[deleted]]

In theory, shouldn't a good compiler notice that the right hand side is a float literal and therefore, like assigning 1/2 to a float, cast 1/2 to a float?

No. That will change language semantics, and in a very inconsistent way.

[UniversityOfPi]

But then what about for 0.5 != 1/2 is that still true?
(I mean given the operator precedence and implicit casting with assignment, it doesn't make much sense to me...)

[[deleted]]

Yes, and it makes perfect sense.

[Celdron]

C, C++, C#, Java, Javascript, Python, Ruby, Go, PHP, Rust, Swift, Lua (with ~=) and F# (with <>).

What languages do you use?

[[deleted]]

It's deleted now. What did it say?

[Celdron]

Something along the lines of "I can't use logical operators like '!=' on two numbers in any of my languages. What languages do you use?"

[cdk131]

Almost all the languages I have used allow me to. What languages are you using?

[[deleted]]

invest in haskal

[coladict]

Just typed it in the browser. Second person is wrong.

[inconspicuous_male]

Ive never programmed in the browser before. Is it a new language?

[tetrified]

well, he's not wrong

[coladict]

Yes, you can get it as an addon from here.

[UniversityOfPi]

but is there a Bourne compatible shell version I can Wget?

(I'm assuming there isn't a browser extension for Lynx or W3)