mirror of
https://github.com/satwikkansal/wtfpython.git
synced 2024-09-11 20:17:08 +03:00
Add new example: Counting the booleans
* Moves the "Booleans are subclass of int" example from "Minor Ones" list to a new example.
This commit is contained in:
parent
82bbded3da
commit
1b8d9ef06a
46
README.md
vendored
46
README.md
vendored
@ -1377,6 +1377,44 @@ Before Python 3.5, the boolean value fo `datetime.time` object was considered to
|
|||||||
|
|
||||||
---
|
---
|
||||||
|
|
||||||
|
### Counting the booleans
|
||||||
|
|
||||||
|
```py
|
||||||
|
# A simple example to count the number of boolean and
|
||||||
|
# integers in an iterable of mixed data types.
|
||||||
|
mixed_list = [False, 1.0, "some_string", 3, True, [], False]
|
||||||
|
integers_found_so_far = 0
|
||||||
|
booleans_found_so_far = 0
|
||||||
|
|
||||||
|
for item in mixed_list:
|
||||||
|
if isinstance(item, int):
|
||||||
|
integers_found_so_far += 1
|
||||||
|
elif isinstance(item, bool):
|
||||||
|
booleans_found_so_far += 1
|
||||||
|
```
|
||||||
|
|
||||||
|
**Outuput:**
|
||||||
|
```py
|
||||||
|
>>> booleans_found_so_far
|
||||||
|
0
|
||||||
|
>>> integers_found_so_far
|
||||||
|
4
|
||||||
|
```
|
||||||
|
|
||||||
|
#### 💡 Explanation:
|
||||||
|
|
||||||
|
* Booleans are a subclass of `int`
|
||||||
|
```py
|
||||||
|
>>> isinstance(True, int)
|
||||||
|
True
|
||||||
|
>>> isinstance(False, int)
|
||||||
|
True
|
||||||
|
```
|
||||||
|
|
||||||
|
* See this StackOverflow [answer](https://stackoverflow.com/a/8169049/4354153) for rationale behind it.
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
### Needle in a Haystack
|
### Needle in a Haystack
|
||||||
|
|
||||||
Almost every Python programmer would have faced this situation.
|
Almost every Python programmer would have faced this situation.
|
||||||
@ -1508,13 +1546,7 @@ a, b = a[b] = {}, 5
|
|||||||
+ `[] = ()` is a semantically correct statement (unpacking an empty `tuple` into an empty `list`)
|
+ `[] = ()` is a semantically correct statement (unpacking an empty `tuple` into an empty `list`)
|
||||||
+ `'a'[0][0][0][0][0]` is also a semantically correct statement as strings are iterable in Python.
|
+ `'a'[0][0][0][0][0]` is also a semantically correct statement as strings are iterable in Python.
|
||||||
+ `3 --0-- 5 == 8` and `--5 == 5` are both semantically correct statments and evalute to `True`.
|
+ `3 --0-- 5 == 8` and `--5 == 5` are both semantically correct statments and evalute to `True`.
|
||||||
* Booleans are a subclass of `int`
|
|
||||||
```py
|
|
||||||
>>> isinstance(True, int)
|
|
||||||
True
|
|
||||||
>>> isinstance(True, float)
|
|
||||||
False
|
|
||||||
```
|
|
||||||
* Python uses 2 bytes for local variable storage in functions. In theory, this means that only 65536 variables can be defined in a function. However, python has a handy solution built in that can be used to store more than 2^16 variable names. The following code demonstrates what happens in the stack when more than 65536 local variables are defined (Warning: This code prints around 2^18 lines of text, so be prepared!):
|
* Python uses 2 bytes for local variable storage in functions. In theory, this means that only 65536 variables can be defined in a function. However, python has a handy solution built in that can be used to store more than 2^16 variable names. The following code demonstrates what happens in the stack when more than 65536 local variables are defined (Warning: This code prints around 2^18 lines of text, so be prepared!):
|
||||||
```py
|
```py
|
||||||
import dis
|
import dis
|
||||||
|
Loading…
Reference in New Issue
Block a user