added for all languages

good choice).. the easiest one)

I had the same type of solution but used do { ... } while (n != 0);
Then if n == 0, the loop will still run at least once.

Also note, this type of solution can do a reasonable thing negatives if you keept track of the sign: -1234 goes to -14916.

Finally, the integer parseInt will throw appropriately if there is integer overflow.

I agree! There should probablt be a special case for that happening, wouldn't be too dificult to fix.

Need a test case like the following: {9,10,14,12,13}
This case would fail several of the accepted answers because they check for more than one instance of prev > current as a fail condition.

Thinking there should be a test case where n is 0. A lot of the solutions that don't convert n to a String will throw an exception if 0 is passed in because we try to Integer.parseInt an empty string.

What happens if n is 0?
I'm thinking parseInt("") is going to throw a conniption fit!