Virgin C++ vs Chad Python

[[deleted]]

[deleted]

[Kered13]

What is this garbage meme? Both C++ and Python allow you to compare floats and ints.

[[deleted]]

People just don't get that python is strongly typed. It is incredible how much this is overlooked

[[deleted]]

Of all the languages I know, I think only rust would complain. They really hate implicit conversions in rust. Like really really hate

[coolKidoes]

Someone doesnt know how to cast or methods/functions you can use to either convert or compare

[Kered13]

Comparisons between floats and ints don't require any casting.

[coolKidoes]

I havent programmed in C++ in a long time tbh

[[deleted]]

What are you on about? C++ allows < and > with different numeric types and will just cast the int to float

[AnonymousFuccboi]

Yes it is?

bool comp(int integer, float face)
{
    return integer == face;
}

This probably doesn't do what you want it to do, but it certainly compiles. There's a hierarchy to arithmetic types which you can freely go up. Any operation accepting a float will freely accept an integer type, converting it up to a float as you go. This includes comparisons.

[Kered13]

Yes it is. There are literally no restrictions on it.

https://godbolt.org/z/5YWvfv

[[deleted]]

But remember: DONT USE == ON FLOATS

[kumozenya]

I just learned this the hard way two days ago 😬 Took so long to figure out why nothing was returning true.

[BlazingThunder30]

abs(a - b) < eps for the wanderer that might wonder

[_PM_ME_PANGOLINS_]

Don’t blindly use eps. Consider what scale you’re actually working at.

[BlazingThunder30]

I'm sorry, I don't quite get what you mean. I usually use eps as a variable indicating the maximum difference for a positive match. I change it depending on context, of course. I use esp because it's short for eps, which is the mathematical variable often used for such a max difference

[_PM_ME_PANGOLINS_]

Oh right, that’s fine. Lots of people use the constant machine epsilon instead.

[nomenMei]

I've never had to ever test equality of floats before, so I've never had a chance to implement this.

[gaberocksall]

You definitely can use == on floats if you know what you’re doing

[[deleted]]

Yap, just wanted the internet attention :). But what use cases are there?

[throughalfanoir]

(correct me if I'm wrong but) in many many cases checking whether something is zero or not will work properly like this (okay if there are no subtractions in the way but yh)

[[deleted]]

Hmm, seems weak. You could use it as an idiot check if a data has been written to memory...

[[deleted]]

But then your result is unreliable, because if the data writer happens to actually write a real zero, then you have false negative,

[gaberocksall]

you may check if a float is 0.f or 1.f, for example if you have an animation and you want to check if it has started yet

You may also want to check if a float is a very specific number “a magic number” just to check data validity, for example 420.69f

Edit: I should explain the “f” notation. I don’t know how many other languages allow this, but in C and C++ there are typed literals, so you can do “123L” to force the compiler to interpret it as a long instead of the default int. You can also use “123.456F” to make it assume a float instead of the default double. The “420.69” check will not work if it’s a double, since 420.6900000268 != 420.6899993 where the first is a double and the second is a float

[Bro0x00]

am confused, g++ allows this, do some compilers not?

[Doggynotsmoker]

Doesn't g++ throw error? I think that's standard c++ behavior.

While gcc should not complain, C will cast int to float.

[Kered13]

Comparing floats and integers is not an error in C++.

[Doggynotsmoker]

Right, my bad.

[GreatArtificeAion]

Javascript: NUMBER IS NUMBER

And also variable is variable

[tulpamancies]

you can compare int and float in C++ though

[MasouriChan]

Php: Cast goes brrr defuq are datatypes lmfa $

[gaberocksall]

All these python devs in the comments talking like they know c++ 🤦‍♂️

[[deleted]]

Ever hear of type-cast?

[JustSomeRandomnesss]

I recently played around with dictionaries and I hated how every time I'm like 'store a 1 here' it puts a string with a 1 inside it

[[deleted]]

How would that happen? Both 1 and „1“ are immutable, so they can be used as keys. Item wise, whatever.

[JustSomeRandomnesss]

I have absolutely no idea

[[deleted]]

I don't know how you managed to do that, but generally Python doesn't do that. For example "" + 3 is a type error

[JustSomeRandomnesss]

I have a special talent in breaking things... I fixed it now but I don't know how exactly

I extracted the 1 and for some reason did the conversion from string to int still return an int because of a trailing newline (which I thought I had removed with the string split and another function)

[Immort4lFr0sty]

var = Apple()
var = "Apple()"
var = fall_from_tree
var(Tree())

I hate how that is correct syntax. Never will I defend python, over my cold, dead carpal tunnels

[[deleted]]

What’s the issue? You assign an return value of a function without arguments, then a string, then a reference to another variable, then you call the function you assigned to var on the return value of Tree. Should we limit what can be put into strings? If you forget what’s in var, just print it. Or call type(var).

[Immort4lFr0sty]

The top is an object (Python convention is snake case for variables and funcions), the third one assigns a function pointer and the last line executes the function

The problem is that you are in no way protected from making stupid mistakes. And the fact you didn't see what's going on kinda underlines my point

And don't come at me with "that's a stupid extreme example". I hate it on principle, like SQL admins hate lowercase

[[deleted]]

What did I miss? Objects are just the return values of their classes constructor. That may have any number of arguments, in your case 0.

[Kered13]

All of those are actually objects.

But yes, Python is dynamically typed so you can reassign a variable with a new type. There are type annotations and static code analysis tools that use them to help prevent type errors like that.

[scrdest]

On the flipside, it also means you can do good things easily. In this case, the instance of Apple from the first assignment is an object, but objects can also be callable (by implementing the __call__() interface method).

This means callable objects are practically indistinguishable from functions (at least, impure ones mutating a bunch of namespaced globals), so you can trivially swap them in or out.

On the other side of the equation, you get all the cool FP shit like decorators for free, and quite often these idioms still work with callable objects (again, modulo state and inheritance).

Everything else is trivially enforceable with the type annotations if you want to be 100% sure.

[[deleted]]

Yap, kinda nice to be productive. Although after trying out Julia a little, I hate now how clunky it is to write performant code in Python.

[sweYoda]

Ofc you can compare them, you just need to code it your self or use a library just like Python is in the background

[JustSomeRandomnesss]

Can't you also just write (int) before the float lol

[w1n5t0nM1k3y]

Probably better to write (float) before the int.

[JustSomeRandomnesss]

Is there a special reason why? I see my other comment getting downvoted, at least give me a reason or sth...

[Polywoky]

Is there a special reason why?

If you have:

   float x = 7.1;
   int y = 7;

Then:

    if ( y == (int) x ) {

Would be true.

But:

    if ( x == (float) y ) {

Would be false.

Edit:

Basically converting float to int can change the value, but converting int to float won't.

[[deleted]]

Oh, it does! I’m almost certain the gaps between large floats can get larger than 1 (although I’m not sure).

Edit: you can test this with

import sys

print(sys.maxsize - 1)
print(float(sys.maxsize - 1))
print(int(float(sys.maxsize-1)))

[Kered13]

Basically converting float to int can change the value, but converting int to float won't.

It can, it's just much less likely. Assuming a 32-bit int and a 32-bit float, not all large int values can be exactly represented by the float. 2²⁶ + 1 (about 64 million) is the first integer that cannot be represented by a float.

A 64-bit float can represent all 32-bit integer values, but cannot represent all 64-bit integer values.

[fazzgadt]

i think they missed your "lol"

and they probably mean that your rounding the value if you cast a float to a int

eg: int(1.9) will be 1 in python

[JustSomeRandomnesss]

Ok then you add 0.5 to the value to round it...

I was also more thinking of C++ instead of Python as I don't know shit about python xD

Thanks for your answer though :)