Sorting digits of an integer

Question

You are given an integer 51234 (say) we need to sort the digits of a number the output will be 12345.

How to do it without using array ?

Answer 1

General overview:

• loop for i = 0 to 9
• in each loop iteration, walk through the digits in the number (using another loop that does a "mod 10" operation to peel off the digits until the number reduces to zero) - if it matches the digit you're currently working on, print it

The only potentially tricky bit might be properly handling zeros - you don't want too many, and you'll want to handle the edge case where the input is zero properly.

Actual implementation is left as an exercise...

Answer 2

You don't need to write a program at all, just do it with shell commands:

echo "51234" | sed 's+\(.\)+\1\n+g' | sort | tr -d '\n'

Answer 3

Create a container interface over the int (something like vector), where operator references the i'th decimal digit. You would have to define iterators and other things too. Then call std::sort on it. ;)