FilesExpand file tree

 master

/

NumberOfDigits.java

Copy path

Blame

More file actions

Blame

More file actions

Latest commit

 

History

History

History

59 lines (54 loc) · 1.65 KB

 master

/

NumberOfDigits.java

Top

File metadata and controls

• Code
• Blame

59 lines (54 loc) · 1.65 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

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);

}

}