Problem of the Day

Problem:

Consider the following method.

public static void mystery(String s)
{
    for (int i = 0; i < s.length(); i++)
    {
        int value = (i + 3) % s.length();
        System.out.print(s.substring(value, value + 1));
    }
    System.out.println();
}

What is printed as a result of the call mystery("infinity");

inityinf
ytinifni
infinity
finityin

Show solution:

The correct answer is a. The i-loop runs once for every character in the string, but it prints out the letter three positions ahead of i. The modulo operator % allows the index to wrap around to the beginning of the word, when i + 3 extends beyond the last character.