如何使用while循环python检查回文

Question

我试图使用while循环和索引检查回文，返回True或False。我知道，使用for循环，甚至只需一行就可以简单得多：return num[：-1]==num
（num是函数中的参数）单击此处查看代码图像

如果有人能告诉我我做错了什么，我很乐意用一段时间来完成这个循环：）

顺便说一下，回文是一个单词或短语，可以用相反的方式阅读，例如：水平，赛车，旋转器等

Answer 1

str = input("Enter a string: ") #taking a string from user & storing into variable.
li = list(str) #converting the string into list & storing into variable.
ln = len(li) #storing the length of the list into a variable.
revStr = "" #defining an empty variable (which will be updated & will be final result to check palindrome).
i = ln - 1 #value of i will be used in loop.

while i >= 0: #here logic is to start from right to left from the list named "li". That means going from last to first index of the list till the index value is "0" of the "li" list.
    revStr = revStr + li[i] #concatenating & updating the "revStr" defined variable.
    i = i - 1 #decreasing the value of i to reach from the last index to first index.
str = str.lower() #converting value into lowercase string.
revStr = revStr.lower() #converting the final output into lowercase string to avoid case sensitive issue.

if str == revStr: #the two string is same or not?
    print(str, ", is PALINDROME!") #if same.
else:
    print(str, ", isn't PALINDROME!") #if not same.

Answer 2

def palindrome(s):
    i = 0
    while i <= len(s) / 2:
        if s[i] != s[-i - 1]:
            return False
        i += 1
    return True

这应该可以了。