Check palindrome

Compare a normalized string with its code-point reversal to test phrase or number symmetry.

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ToolPalindrome Checker
Input
Output
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Preview

How it works

The source can be lowercased and stripped of whitespace, ASCII-oriented punctuation, and digits before Unicode code points are reversed. Equality is exact after those selected normalizations.

  • Case, spaces, and punctuation are ignored first to recognize phrases such as A man, a plan, a canal: Panama.
  • Digits remain because numeric palindromes are meaningful inputs.

Worked example

Check a palindrome phrase
Verify if a sentence reads the same forwards and backwards
Input
											A man, a plan, a canal: Panama
Output
												Is palindrome: yes
Normalized: amanaplanacanalpanama
Reversed: amanaplanacanalpanama

When to use this

Classroom exercises normalize phrase palindromes, puzzle solvers check candidates, and tests verify ASCII reversal routines.

Edge cases

  • Many non-Latin letters are removed by the ASCII word-character filter instead of being compared.
  • e plus a combining acute accent reverses as two code points and can fail despite a symmetric-looking display.
  • Ignoring digits can turn 1a2a1 into aa, changing the test to letter-only symmetry.

References