Python传值与传址

Posted 2022-09-01 算法与编程之美

问题

传值还是传址是Python程序设计中最容易混淆和出错的一类编程方式。

方法

传值

'''
(1) 数字
'''
a = 1

def foo1(a):
    a = 10

foo1(a)
print(f'a = a') # 1

'''
(2) 字符串
'''
b = 'hello'

def foo2(b):
    b = 'world'

foo2(b) 
print(f'b = b') # hello

'''
(3) 元组
'''
c = (1,2,3)

def foo3(c):
    c = (4,5,6)
    
foo3(c)
print(f'c = c') # (1, 2, 3)

传址

'''
(1) 列表
'''
a = [1,2,3]

def foo1(a):
    a[0] = 5
    a[1] = 5
    a[2] = 5

foo1(a)
print(f'a = a') # a = [5, 5, 5]

'''
(2) 字典
'''
b = 'name':'chen'

def foo2(b):
    b['name'] = 'zhen'
    
foo2(b)
print(f'b = b') # b = 'name': 'zhen'


'''
(3) 对象
'''
class User:
    def __init(self):
        self.username = 'chen'
        
def foo4(user):
    user.username = 'zhen'
    
u = User()
foo4(u)
print(f'user = u.username') # user = zhen

结语

• 数字、字符串、元组是传值；
• 列表、字典是传址。