如何捕获 Python 中的特定索引错误并为此附加新值？

Question

我想 return None 仅当我发现索引超出问题值的范围时

 def extract_values(values):
     try:
         first = values[0]
         second = values[1]
         last = values[3]
     except IndexError:
        first = "None"
         last = "None"
        second = "None"
     return first,second,last
 # test
 list_values = ["a","b","c"]    
 print(extract_values(list_values))


actual result with this code :
('None', 'None', 'None') 
missed result  :
('a', 'b', 'None')

Answer 1

肯定有一个更优雅的答案，但你可以这样做：

def extract_values(values):
    try:
        first = values[0]
    except IndexError:
        first = None
    try:
        second = values[1]
    except IndexError:
        second = None
    try:
        third = values[3]
    except IndexError:
        third = None
    return first, second, third

如何捕获 Python 中的特定索引错误并为此附加新值？

How to catch specific index error in Python and attach new value for this?

python

try-except

index-error