Boolean

python有別的寫法

Python裡的Boolean不叫boolean，是「bool」。

a = True
b = False
print(a and b) #False
print(a or b) #True
print(not a) #False

在做if判斷時，「非」的寫法可以直接寫「not」(用「~」反而會無效)

if not result.__contains__(value):

&

python中沒有「&&, ||」這種「兩個&|」的符號(其他語言中視為and, or)，寫為「and, or」

EX

a = None
b = "S"
print(a is None) # >True
print(b is None) # >False
print(a is None and b is None) # >False
print(a & b) # >TypeError: unsupported operand type(s) for &: 'NoneType' and 'stry

數值EX

a = 7
b = 3
print(a is None) # >False
print(b is None) # >False
print(a is None and b is None) # >False
print(a & b) # >3

print(a is None & b is None)
# >TypeError: unsupported operand type(s) for &: 'NoneType' and 'int' =>「X is None」的回傳是個NoneType的物件

基本上一般會用到的會是「and, or」!

Transfer type

string to boolean

bool(str)

python視任何object為「truthy」，其值非空時布林為True，空值時為False；所以只有空字串為False。

EX

print(bool('True'))  # >True
print(bool(''))  # >False
print(bool('X'))  # >True
print(bool(0))  # >False
print(bool(3))  # >True