checking an integer to see if it contains a zero

Question

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

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

How c

Answer 1

Here is a routine that will work detect zeros in integers. To make it work with any representation (decimal, hex, octal, binary), you need to pass in 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)
}