Question

sub如何打印24，因为i将得到['24']，而sub应该只运行一次？而且我完全困惑sub如何显示整数24，因为inner for循环只会运行一次。

l1=[['24']]
for i in l1:
    print(i)
    for sub in i:
        print(sub)

输出为：

['24']
24

Answer 1

如果您不了解自己的输出，请向其添加更多打印（和/或数据），直到执行以下操作：

l1=[['24',"Y"],"X"]
for i in l1:                   # iterates all elements of the outer list
    print("i is:",i, type(i))
    for sub in i:              # iterates all elements of the inner list
        print("sub is:",sub, type(sub))
        for s in sub:          # iterates the single characters of your string
            print("s is:",s,type(s))

输出（格式化）：

i is: ['24', 'Y'] <class 'list'>
    sub is: 24 <class 'str'>
        s is: 2 <class 'str'>
        s is: 4 <class 'str'>
    sub is: Y <class 'str'>
        s is: Y <class 'str'>
i is: X <class 'str'>
    sub is: X <class 'str'>
        s is: X <class 'str'>

请参见How to debug small programs

sub如何执行？

1 个答案: