Question

A. 基本情况但是,检查职能是否恢复某些价值的最佳方式是什么?

def hillupillu():
    a= None
    b="lillestalle"
    return a,b

if i and j in hillupillu(): #how can i check if i or j are empty? this is not doing it of course;-P
    print i,j

Answer 1

如果你意味着你可以预测某些职能的回报价值的数量,那么,

i, j = hillupillu()

如果该功能确实有两个价值,则将产生<代码>ValueError。您可以按照通常的<条码>、收集。构造:

try:
    i, j = hillupillu()
except ValueError:
    print("Hey, I was expecting two values!")

This follows the common Python idiom of "asking for forgiveness, not permission". If hillupillu might raise a ValueError itself, you ll want to do an explicit check:

r = hillupillu()
if len(r) != 2:  # maybe check whether it s a tuple as well with isinstance(r, tuple)
    print("Hey, I was expecting two values!")
i, j = r

If you meant that you want to check for None in the returned values, then check for None in (i, j) in an if-clause.

Answer 2

灰色功能总回报一个价值。尤其是,他们可以回教。

如果你不了解图中有多少价值,你可以检查其长度:

tuple_ = hillupillu()
i = tuple_[0] if tuple_ else None
j = tuple_[1] if len(tuple_) > 1 else None

Answer 3

在从职能中获得价值后:

i, j = hillupillu()

您可核实价值是否为None和is的操作者:

if i is None: ...

你们也可以只是检验真相价值的价值:

if i: ...

Answer 4

if(i == "" or j == ""):
   //execute code

象这样说,但如果你给它一个<代码>的话。页: 1

if(i == None or j == None):
    //execute code

希望

Answer 5

您可以核实该职能的回报价值是否为:

r_value = foo(False)

x, y = None, None
if type(r_value) == tuple:
    x, y = r_value
else:
    x = r_value
    
print(x, y)

举例来说,如果已知该功能可以收回一个精确的长度2的图形(例如,采用<代码>return a, b),或一个单一的数值,则该功能就属于这种情况。它可以扩大到处理其他职能可以退还其他期限的拖.的情况。

我不认为“Foo”的接受答案是正确的,原因有几个:

It will happily unpack other iterables that can be unpacked into two values, such as a list or string of lengths 2. This does not correspond to a return from a function that returned multiple values.
The thrown exception can be TypeError, not a ValueError.
The variables that store the return value are scoped to the try block, and so we can only deal with them inside that block.
It doesn t show how to handle the case where there is a single returned value.

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