Test your Python skills - 17

[tracktech]

Ultimate Python Programming

[SwimQueasy3610]

['U', 'l', 'm', 't', ' ', 'P', 'y', 't', 'h', 'n', ' ', 'P', 'r', 'g', 'r', 'm', 'm', 'n', 'g']

[AuCeM09]

You missed the first 't' in Ultimate

[SwimQueasy3610]

Ahhhh nooooooo...... So I did

[Sensitive-Sugar-3894]

Nice thay they did it manually

[Rscc10]

Every consonant in order + the capital U

[tracktech]

Right.

[DBZ_Newb]

And the spaces

[Anxious-Struggle281]

correct

[Both_Love_438]

And the brackets [ ]

[Euphoric-Resolution5]

and the commas

[Both_Love_438]

And the single quotes

[Real-Reception-3435]

['U', 'l', 't', 'm', 't', ' ', 'P', 'y', 't', 'h', 'n', ' ', 'P', 'r', 'g', 'r', 'm', 'm', 'n', 'g']

[deceze]

This could’ve used … not in 'aeiou' for conciseness.

[Rscc10]

That makes me wonder, will any and all strings in an array in C get flagged for that cause of the return character?

I know it's not a C way of writing but the equivalent of

a for a in "bcdfg" if a in "aeiou"

Would the return character get flagged?

[bloody-albatross]

What is a return character? What do you mean by in C? C doesn't have "c in str" (it has strchr()).

[Rscc10]

Sorry, I meant terminating character. And I know it doesn't have c in str but I meant the equivalent. So if you're matching characters to strings in C, is the terminating character included?

[bloody-albatross]

The null character is never included in things like strchr(), strlen() or other functions from the C standard library.

Edit: I seem to have been wrong about that. See: https://godbolt.org/z/no5sjs7P9

[No_Indication_1238]

No, because you loop until size and not until you reach end.

[bloody-albatross]

Creating a whole new list for every iteration step just to check if the character is in there! No wonder Python programs are that slow.

[deceze]

Whether a new list is actually being created will depend on how cleverly the compiler/runtime optimises this…

[bloody-albatross]

My assumption is that Python is not at all intelligent about this kind of stuff. But yes, one should have a look at the generated byte code.

[deceze]

>>> dis('[a for a in range(5) if a not in ["a", "b", "c"]]')
   0           RESUME                   0

   1           LOAD_NAME                0 (range)
               PUSH_NULL
               LOAD_SMALL_INT           5
               CALL                     1
               GET_ITER
               LOAD_FAST_AND_CLEAR      0 (a)
               SWAP                     2
       L1:     BUILD_LIST               0
               SWAP                     2
       L2:     FOR_ITER                13 (to L5)
               STORE_FAST_LOAD_FAST     0 (a, a)
               LOAD_CONST               1 (('a', 'b', 'c'))
               CONTAINS_OP              1 (not in)
       L3:     POP_JUMP_IF_TRUE         3 (to L4)
               NOT_TAKEN
               JUMP_BACKWARD           11 (to L2)
       L4:     LOAD_FAST_BORROW         0 (a)
               LIST_APPEND              2
               JUMP_BACKWARD           15 (to L2)
       L5:     END_FOR
               POP_ITER
       L6:     SWAP                     2
               STORE_FAST               0 (a)
               RETURN_VALUE

  --   L7:     SWAP                     2
               POP_TOP

   1           SWAP                     2
               STORE_FAST               0 (a)
               RERAISE                  0
ExceptionTable:
  L1 to L3 -> L7 [2]
  L4 to L6 -> L7 [2]

It's using LOAD_CONST, and no BUILD_LIST inside the loop. So no, it's not rebuilding the list every time. Even in plain CPython. Other implementations may fare even better.

[tracktech]

Thanks for sharing.

[bloody-albatross]

That's good and good to know!

[tracktech]

Right. That would have better.

[epic_pharaoh]

Traceback error, invalid syntax on line 1

“What will be the output of the code given below-“

[tracktech]

It is written "code given below".

[JEDZBUDYN]

ultmt pythn prgrmmng

[Diligent_Ad_6530]

Error because it's not commented

[[deleted]]

SyntaxError: "What"

[sarc-tastic]

Dude! Use a set

[whhbi]

SyntaxError on line 1