package Maths;

/** Find the number of digits in a number. */
public class NumberOfDigits {
 public static void main(String[] args) {
 int[] numbers = {0, 12, 123, 1234, -12345, 123456, 1234567, 12345678, 123456789};
 for (int i = 0; i < numbers.length; ++i) {
 assert numberOfDigits(numbers[i]) == i + 1;
 assert numberOfDigitsFast(numbers[i]) == i + 1;
 assert numberOfDigitsFaster(numbers[i]) == i + 1;
 assert numberOfDigitsRecursion(numbers[i]) == i + 1;
 }
 }

 /**
 * Find the number of digits in a number.
 *
 * @param number number to find
 * @return number of digits of given number
 */
 private static int numberOfDigits(int number) {
 int digits = 0;
 do {
 digits++;
 number /= 10;
 } while (number != 0);
 return digits;
 }

 /**
 * Find the number of digits in a number fast version.
 *
 * @param number number to find
 * @return number of digits of given number
 */
 private static int numberOfDigitsFast(int number) {
 return number == 0 ? 1 : (int) Math.floor(Math.log10(Math.abs(number)) + 1);
 }

 /**
 * Find the number of digits in a number faster version.
 *
 * @param number number to find
 * @return number of digits of given number
 */
 private static int numberOfDigitsFaster(int number) {
 return number < 0 ? (-number + "").length() : (number + "").length();
 }

 /**
 * Find the number of digits in a number using recursion.
 *
 * @param number number to find
 * @return number of digits of given number
 */
 private static int numberOfDigitsRecursion(int number) {
 return number / 10 == 0 ? 1 : 1 + numberOfDigitsRecursion(number / 10);
 }
}