Question

How to recursively check if a number is palindrome in Pascal

Answer 1

program CheckPalindrome;

function IsPalindrome(num, reversed, original: Integer): Boolean;
begin
    // Base case: If the number is reduced to 0, check the reverse against the original number
    if num = 0 then
        IsPalindrome := (reversed = original)
    else
    begin
        // Extract the last digit, update the reversed number, and proceed recursively
        reversed := reversed * 10 + (num mod 10);
        IsPalindrome := IsPalindrome(num div 10, reversed, original);
    end;
end;

var
    number: Integer;
    result: Boolean;
begin
    number := 12321;

    // Call the recursive function
    result := IsPalindrome(number, 0, number);

    if result then
        WriteLn(number, ' is a palindrome.')
    else
        WriteLn(number, ' is not a palindrome.');
end.



(*
run:

12321 is a palindrome.

*)

 

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