TA貢獻(xiàn)1934條經(jīng)驗(yàn) 獲得超2個(gè)贊
if len(my_list) != 0: print "Not empty!"
if my_list: print "Not empty!"
[][1]
TA貢獻(xiàn)1841條經(jīng)驗(yàn) 獲得超3個(gè)贊
None
False
0
0.0
0j
Decimal(0)
Fraction(0, 1)
[]
list
{}
dict
()
tuple
''
str
b''
bytes
set()
set
range
range(0)
obj.__bool__()
False
obj.__len__()
0
ifwhileboolTrueFalse.
TA貢獻(xiàn)1852條經(jīng)驗(yàn) 獲得超1個(gè)贊
bool()TrueFalseifwhile.
Vector2dFalseTrue.
import mathclass Vector2d(object): def __init__(self, x, y): self.x = float(x) self.y = float(y) def __abs__(self): return math.hypot(self.x, self.y) def __bool__(self): return bool(abs(self))a = Vector2d(0,0)print(bool(a)) #Falseb = Vector2d(10,0) print(bool(b)) #True
注：__bool__
舉報(bào)