Python - 我无法理解这个错误

Question

我正在尝试编写一个程序，要求用户输入 4 个整数并打印输入的最大奇数。这是代码:

a = raw_input("Enter an int: ")
b = raw_input("Enter an int: ")
c = raw_input("Enter an int: ")
d = raw_input("Enter an int: ")

numbers = [a, b, c, d]
odd_numbers = []
print numbers
for i in numbers:
    if i%2!=0:
        odd_numbers.append(i)
    else:
        print "This is not an odd number."


for nums in odd_numbers:
    max_num = max(odd_numbers)
    print max_num

这是我收到的错误:

line 10, in <module>
  if i%2!=0:
TypeError: not all arguments converted during string formatting

我做错了什么？

Answer 1

raw_input()返回一个字符串。结果，numbers 列表变成了字符串列表。 % 操作行为取决于变量类型，如果是字符串，则为 string formatting操作:

>>> s = "3"
>>> s % 2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: not all arguments converted during string formatting

如果是 int，它会为您提供 division remainder :

>>> n = 3
>>> n % 2
1

您需要将所有输入转换为int:

a = int(raw_input("Enter an int: "))
b = int(raw_input("Enter an int: "))
c = int(raw_input("Enter an int: "))
d = int(raw_input("Enter an int: "))

为了避免出现冗余代码，您可以使用 list comprehension 简化填充数字列表。 :

numbers = [int(raw_input("Enter an int: ")) for _ in xrange(4)]