[Python] 비슷한 연산자의 차이(is, ==, and, &, or, |)

kkiyou·2021년 5월 24일

python

Python

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1. 'is' and '=='

1.1. 'is'

객체의 주소값이 같으면 True를 반환한다.

Object Identity Operator
Reference Comparison (참조 비교)

1.2. `==`

객체의 값이 같으면 True를 반환한다.

Equal Comparison Operator(비교 연산자)
Value Comparison (값 비교)

a = 10
b = 10
print("a is b =", a is b)
print("a == b =", a == b)
print("id(a) =", id(a))
print("id(b) =", id(b))

a is b = True
a == b = True
id(a) = 4545772160
id(b) = 4545772160

a = 999
b = 999
print("a is b =", a is b)
print("a == b =", a == b)
print("id(a) =", id(a))
print("id(b) =", id(b))

a is b = False
a == b = True
id(a) = 140654371171984
id(b) = 140654371172112

10과 999의 문법적 차이는 존재하지 않음에도 주소값이 다른 이유는 파이썬의 Default 값이 Object Interning을 사용하기 때문이다.
참고자료1 참고자료2

2. 'and' and '&'

2.1. 'and'

Logical Operator(논리 연산자)
True/False 연산
x and y: if x is false, then x, else y
- First argument(x) is True -> evaluates second argument(y)
- First argument(x) is False -> False

>>> print(1 and 9) # 1 is True -> 9 is True -> print 9
9
>>> print(2 and 9) # 2 is True -> 9 is True -> print 9
9
>>> print(1 and 0) # 1 is True -> 0 is False -> print 0
0
>>> print(0 and 1) # 0 is False -> print 0
0
>>> print(0 and 0) # 0 is False -> print 0
0
>>> print(bin(0b1010 and 0b1111)) # 0b1010 is True -> 0b1111 is True -> print 0b1111
0b1111

2.2. '&'

Comparison Operator(비교 연산자)
Bitwise 연산

>>> print(1 & 9) # True & True -> True is 1
1
>>> print(2 & 9) # True & True -> True is 1
1
>>> print(1 & 0) # True & False -> Fales is 0
0
>>> print(0 & 1) # False & True -> Fales is 0
0
>>> print(0 & 0) # False & False -> Fales is 0
0
>>> print(bin(0b1010 & 0b1111)) # Bitwise calculation
0b1010

3. 'or' and '|'

3.1. 'or'

Logical Operator(논리 연산자)
True/False 연산
x or y: if x is false, then y, else x
- First argument(x) is True
- First argument(x) is False -> evaluates second argument(y)

>>> print(1 or 9) # 1 is True -> 9 is True -> print 1
1
>>> print(2 or 9) # 2 is True -> 9 is True -> print 2
2
>>> print(1 or 0) # 1 is True -> 0 is False -> print 2
1
>>> print(0 or 1) # 0 is False -> 1 is True -> print 1
1
>>> print(0 or 0) # 0 is False -> 0 is False -> print 0
0
>>> print(bin(0b1010 or 0b1111)) # 0b1010 is True -> 0b1111 is True -> print 1010
0b1010

3.2. '|'

Comparison Operator(비교 연산자)
Bitwise 연산

>>> print(1 | 9) # 0b0001 | 0b1001 = 0b1001
9
>>> print(2 | 9) # 0b0010 | 0b1001 = 0b1011
11
>>> print(1 | 0) # 0b0001 | 0b0000 = 0b0001
1
>>> print(0 | 1) # 0b0000 | 0b0001 = 0b0001
1
>>> print(0 | 0) # 0b0000 | 0b0000 = 0b0000
0
>>> print(bin(0b1010 | 0b1111)) # 0b1010 | 0b1111 = 0b1111
0b1111

4. 'not' and '~'

4.1. 'not'

Logical Operator(논리 연산자)
True/False 연산
if x is false, then True, else False
- Argument(x) is True -> False
- Argument(x) is False -> True

>>> print(not(0)) # 0 is False
True
>>> print(not(9)) # 9 is True
False

4.2. '~'

Comparison Operator(비교 연산자)
Bitwise 연산

>>> print(~0) # 0b0000의 보수 = 0b1111 = -1
-1
>>> print(~7) # 0b0111의 보수 = 0b1000 = -8
-8
Decimal value 4bits binary
7 0 111
6 0 110
5 0 101
4 0 100
3 0 011
2 0 010
1 0 001
0 0 000
-1 1 111
-2 1 110
-3 1 101
-4 1 100
-5 1 011
-6 1 010
-7 1 001
-8 1 000