为什么这个 for 循环有效，而 function 无效？

Question

谁能向我解释为什么这段代码有效：

data = "8 (including George Blake, aged 69, and Robert Reynolds, aged 12)"
chars = "()[]?+"
for ch in chars:
    if ch in data:
        data = data.replace(ch,"")
print(data)

但是当我尝试创建一个 function 来对这段代码做同样的事情时，我得到的 output 是无：

def clean(data):
chars = "()[]?+"
for ch in chars:
    if ch in data:
        data = data.replace(ch," ")
bob = "8 (including George Blake, aged 69, and Robert Reynolds, aged 12)"
print(bob)
output = clean(bob)
print(output)

Answer 1

当您将数据作为参数传递给 function 并声明data = data.replace(ch, "")时，您正在修改参数，而不是传递给 function 的原始数据。 您应该尝试在 function 末尾return data ，然后将其值分配给 output，例如：

def clean(data):
chars = "()[]?+"
for ch in chars:
    if ch in data:
        data = data.replace(ch," ")
return data
bob = "8 (including George Blake, aged 69, and Robert Reynolds, aged 12)"
print(bob)
output = clean(bob)
print(output)