Python 的len(s)
函式可取得物件的長度。
傳入的參數可以是序列(string, bytes, list, tuple)或集合(dictionary, set, frozen set)。如果是物件則會回傳實作__len__
函式的回傳結果。
一些範例。
s = "hello world" # string
print(len(s)) # 11
int_list = [1,2,3,4,5] # list
print(len(int_list)) # 5
int_list = range(0, 10)
print(len(int_list)) # 9
b = b'hello world' # bytes
print(len(b)) # 11
t = ("hello", "world") # tuple
print(len(t)) # 2
int_set = {1, 2, 3} # set
print(len(int_set)) # 3
dict_employee = {'name':'John', 'age':27} # dictionary
print(len(dict_employee)) # 2
class Employee:
def __init__(self, name, age):
self.name = name # instance variable
self.age = age # instance variable
def __len__(self):
return len(self.name) + self.age
employee = Employee('John', 27) # create Employee instance 'employee'
print(len(employee)) # 31 (4 + 27)
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