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.