Checking an integer to see if it contains zero

Question

Given an integer, how can you check if it contains 0 using Java?

  1 = Good
 2 = Good
 ...
 9 = Good
 10 = BAD!
 101 = BAD!
 1026 = BAD!
 1111 = Good

How can I do that?

Answer 1

Do you mean if the decimal notation contains 0? The absolute easiest way to do this:

if (String.valueOf(x).contains("0")) 

Do not forget that the number is not "in fact" contains 0 or not (except for zero itself, of course) - it depends on the base. So, “10” in decimal “A” in hexadecimal, and “10” in hexadecimal “16” in decimal ... in both cases, the result has changed.

There may be more effective ways to test for the presence of zero in the decimal representation of an integer, but they are likely to be significantly more involved in the expression above.

Answer 2

If for some reason you don't like the solution that converts to String, you can try:

 boolean containsZero(int num) { if(num == 0) return true; if(num < 0) num = -num; while(num > 0) { if(num % 10 == 0) return true; num /= 10; } return false; } 

This also assumes num is base 10.

Edit: Added conditions for working with negative numbers and 0 themselves.

Answer 3

You can convert it to a string and check if it contains char "0".

 int number = 101; if( ( "" + number ).contains( "0" ) ) { System.out.println( "contains the digit 0" ); } 

Answer 4

Integer.toString(yourIntValue).contains("0");

Answer 5

Here is a routine that will work with detecting zeros in integers. To make it work with any representation (decimal, hexadecimal, octal, binary), you need to pass the base as a parameter.

 public static boolean hasZero(int num, int base) { assert base > 0 : "must have positive non-zero base"; if (num == 0) return true; while(num != 0) { if (num % base == 0) { return true; } else { num = num / base; } } return false; } public static void main(String args[]) { System.out.println(hasZero(10, 10)); // true (base 10 int) System.out.println(hasZero(-12, 10)); // false (base 10 int) System.out.println(hasZero(0x10, 16)); // true (hex is base 16) System.out.println(hasZero(0x1A, 16)); // false (hex is base 16) } 

Answer 6

I don’t know if this is easier, but here is another way. Divide the number by an int array. Then sort and check if the first element is zero. For example,

 int n = 14501; // after splitting int na = {1, 4, 5, 0, 1}; // after sorting int na = {0, 1, 1, 4, 5}; 

Answer 7

Not using Java, but it is not at all difficult to convert from C ++ PS. Shame on anyone using string conversion.

 bool Contains0InBase10( unsigned int i, unsigned int& next ) { unsigned int divisor = 10; unsigned int remainder = 0; while( divisor <= i ) { unsigned int newRemainder = i%divisor; if( newRemainder - remainder == 0) { // give back information allowing a program to skip closer to the next // number that doesn't contain 0 next = i + (divisor / 10) - remainder; return true; } divisor *= 10; remainder = newRemainder; } return false; }