digit-reverse – Reverse decimal digits – Computer Science by Example

digit-reverse – Reverse decimal digits

Write a program that reads several integers, reverses their digits and prints the result. For example:

if we reverse the digits of 720 we end up with 27;
if we reverse the digits of 1234 we end up with 4321.

Reversing the digits of 720 and 1234

Input and Output

Input will consist of several lines each with a number d where 0 ≤ d ≤ 1 000 000 000. You should ignore leading zeroes on d if they are present.

For each line of input, output should contain a single line with a number b with the reversed digits of d. Do not print leading zeroes on b.

Input is terminated by the end-of-file (EOF).

Example input

Example output

The “reverse digits” function

Your program should be implemented using a “reverse digits” function that receives one integer and returns an integer with the reversed digits. Please refer to the information for the chosen language:

Python definition: def reverse_digits(x):
C prototype: int reverse_digits(int x);
Haskell type: reverseDigits :: Int -> Int
C++ prototype: int reverse_digits(int x);
C# definition: public static int ReverseDigits(int x) in a public class Program
Java definition: public static int reverseDigits(int x) in a public class DigitReverse
JavaScript definition: function reverse_digits(x)
Lua definition: function reverse_digits (x)
Ruby definition: def reverse_digits(x)

Scoring

Submit your solution to be graded according to the following list:

1/6: works for the above example but produces output in an incorrect format
2/6: works for the above example and produces output in the correct format
4/6: works for other test cases
5/6: works for edge cases
6/6: implements the “reverse digits” function

Hints

If you have difficulty with this exercise, try digit-sum or digit-count first.

try first: digit-count digit-sum oddeven

try next: digit-palindrome

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