Palindromes
A palindrome is a number, word, or sentence that reads the same from left to right and right to left. Use PalindromeQ, its options, and other string-related low-level functions to test for palindromic words and sentences.
This is an English palindrome.
In[1]:=
![Click for copyable input](assets.en/palindromes/In_17.png)
PalindromeQ["racecar"]
Out[1]=
![](assets.en/palindromes/O_13.png)
The name Anna is also a palindrome, but you need to ignore the capitalization.
In[2]:=
![Click for copyable input](assets.en/palindromes/In_18.png)
PalindromeQ["Anna", IgnoreCase -> True]
Out[2]=
![](assets.en/palindromes/O_14.png)
Use Decapitalize as an alternative to make the first character be lowercase.
In[3]:=
![Click for copyable input](assets.en/palindromes/In_19.png)
PalindromeQ[Decapitalize["Anna"]]
Out[3]=
![](assets.en/palindromes/O_15.png)
The French verb "rêver" is a palindrome as well, but you need to ignore the diacritic.
In[4]:=
![Click for copyable input](assets.en/palindromes/In_20.png)
PalindromeQ["rêver", IgnoreDiacritics -> True]
Out[4]=
![](assets.en/palindromes/O_16.png)
Use RemoveDiacritics to process the verb instead.
In[5]:=
![Click for copyable input](assets.en/palindromes/In_21.png)
PalindromeQ[RemoveDiacritics["rêver"]]
Out[5]=
![](assets.en/palindromes/O_17.png)
With palindromic sentences, you also generally need to process the initial string.
In[6]:=
![Click for copyable input](assets.en/palindromes/In_22.png)
sentence = "Now, sir, a war is won!";
In[7]:=
![Click for copyable input](assets.en/palindromes/In_23.png)
PalindromeQ[sentence]
Out[7]=
![](assets.en/palindromes/O_18.png)
In[8]:=
![Click for copyable input](assets.en/palindromes/In_24.png)
StringDelete[sentence, PunctuationCharacter | Whitespace]
Out[8]=
![](assets.en/palindromes/O_19.png)
In[9]:=
![Click for copyable input](assets.en/palindromes/In_25.png)
StringDelete[sentence, PunctuationCharacter | Whitespace];
PalindromeQ[%, IgnoreCase -> True]
Out[9]=
![](assets.en/palindromes/O_20.png)