How to Accurately Detect Palindromes in Python: Multiple Approaches Explained

The author received a question in a Python community about checking whether a number is a palindrome.

The original attempt was:

x=input("请输入一个正整数：")
long=len(x)
end=str(x[long-1])
end=int(end)
x=int(x)

if x<0 or end ==0:
    print("不是回文数")
else:
    x=str(x)
    for i in range(len(x)):
        if x[i]==x[long-i-1]:
            continue
        else:
            print("不是回文数")
            break
    else:
        print("是回文数")

The issue was where to place the statement that prints “是回文数”.

Implementation

One user suggested a solution illustrated below:

Another suggestion was to put the print statement inside a for‑else block, resulting in the updated code shown above.

Additional approaches were provided:

Using all() with a comprehension to compare characters:

d = ['12321', '123', '1221', '1212']
for s in d:
    l = len(s)
    if all(s[i] == s[l-i-1] for i in range(l)):
        print(f'{s}是回文数')
    else:
        print(f'{s}不是回文数')

Using slicing s[::-1] to reverse the string:

d = ['12321', '123', '1221', '1212']
for s in d:
    if s == s[::-1]:
        print(f'{s}是回文数')
    else:
        print(f'{s}不是回文数')

An explanatory image about the for‑else behavior is shown below:

Conclusion

The article summarizes the palindrome‑checking problem, presents several correct Python implementations, and explains the logic behind each approach, helping readers solve similar algorithmic questions.