if coin == 25 | 10 | 5:

If I replace the ‘|’ with ‘or’ the code runs just fine. I’m not sure why I can’t use ‘|’ in the same statement.

Doing the following doesn’t work either:

if coin == 25 | coin == 10 | coin == 5:

I know bitwise operators can only be used with integers, but other then that is there another difference from logical operators?

  • milon@lemm.eeOP
    1·
    2 个月前

    Thanks. I think I understand why I wouldn’t want to use it in this case. But what is an example of where I can use it? This makes me think I should avoid using bitwise operators with integers and keep it to strings only, but I know that’s not true from what I’ve learned.

    • driving_crooner@lemmy.eco.br
      1·
      2 个月前

      I use that in match case operations, but usually when is just two possibilities, try something like this and see if works

      match coin:
      case 5 | 10 | 20:
      …

      Edit: just tested and it’s works.

    • wewbull@feddit.ukEnglish
      1·
      2 个月前

      When you’re working with the binary representation of numbers.

      In your code you had three numbers 25, 10 and 5. If we write those number in binary we get:

      • 25: 0b00011001
      • 10: 0b00001010
      • 5: 0b00000101

      (The 0b at the start is just a way of saying “this is binary”)

      When you do a bitwise-or, it’s a bit like adding up but you don’t bother with carrying anything. So let’s do 25 | 10, starting at the right-hand end going bit by bit (bitwise):

      • 0 | 1 = 1
      • 1 | 0 = 1
      • 0 | 0 = 0
      • 1 | 1 = 1
      • 1 | 0 = 1
      • 0 | 0 = 0 for all the rest

      So the result is 0b00011011 which is 27.

      So now you’re asking “when would I ever need to do such a thing?” and the flippant answer is “you’ll know when you need it”.

      You’re looking for more though, I know. Basically computers often put multiple bits of data into bitstreams (long sequences of bits). Think networking and file storage. Constructing these bitstreams is done with bitwise operators like |, &, ^, << and >>. Together they form a different type of maths to what you’re used to.

      These operators work in a very similar way to how +, -, * and / work. They take two numbers and return a third. If we rewrite your code using operators you’re more familiar with…

          if coin == 25 | 10 | 5:  # if coin == 31
        ...
    if coin == 25 + 10 + 5:  # if coin == 40
        ...

      …you can see it’s obviously wrong because you’re doing one comparison with the result of the operation (addition or bitwise-or), not three comparisons.

    • ExtremeDullard@lemmy.sdf.org
      1·
      2 个月前

      But what is an example of where I can use it?

      Aside from operations on bitfields, a bitwise operator can be useful in several “non bits” cases. For instance:

      value & 1 evaluates to 1 if value is odd (and will evaluate to True in an if statement)
      value >> 1 divides value by 2 (integer division)

      But usually bitwise operators are for when you want to manipulate bits in values. For instance:

      value | 5 returns value with bits 1 and 3 set to True
      value & 0xffff returns the 16 least-significant bits in value (usually you do this to make sure it will fit in 2 bytes in memory for example)
      value & (0xffff ^ 5) returns the lower 16 bits of value with bits 1 and 3 set to False

      Etc.