python中的字符串到整数函数

Question

我希望能够将距离列表从英里更改为公里，其中英里列表用以下代码位获得：

input_string = input("Enter a list of distances, separated by spaces").strip()

要将输入列表更改为整数列表，我使用：

distances = input_string.split()
print("This is what you entered: ")
for distance in distances:
     print(distance)

def str2int(word):
    """Converts the list of string of miles into a list of integers of miles"""
    integer = int(word)
    if int(word):
        return integer
    else:
        sys.exit("Please try again and enter a list of integers.")


def validate_all(distances):
    """
    Checks if all the inputs are integers. If not all are integers, sys.exit
    without converting any of the distances and ask to try again.
    """

    true_list = []

    for distance in distances:
        if str2int(distance):
            true_list.append(distance)

    if len(distances) == len(true_list):
        return True
    else:
        return False

print("And now, we are going to convert the first one to kilometers:")
miles = distances[0]

if validate_all:
    # now, the calculation and display
    kms = miles_int * KMPERMILE
    print("The first distance you entered, in kilometers:", kms)

    for i in range(1, len(distances), 1):
        miles_int = str2int(distances[i])
        kms = miles_int * KMPERMILE
        print("The next distance you entered in kilometres:", kms)

但是，当我试图检查字符串列表中的所有元素是否都可以更改为整数（使用validate_all（word））并具有如下内容时

12 23 apples banana 5

作为我的输入，程序崩溃，说在

str2int(word)
-> if int(word):

而不是我拿到系统出口

有人能帮我调试一下这个吗？